You could tune in and watch and pretend you were there, or you could tune in and watch and be wildly grateful that you weren't there. Either way, Live Aid, the monstrously massive rock concert fundraiser that dominated the airwaves Saturday, was a watershed media event.

Times and television having changed, people who saw it won't have to tell their grandchildren about it. They'll be able to play them a videotape. Video stores in this area and others were reporting higher than usual demand for blank cassettes and rented VCRs as Live Aid approached late last week.

Watching the hours and hours of live coverage Saturday was something like being trapped inside a popcorn-popper time capsule. Here was Joan Baez, our lady of the '60s, one moment, and here was Madonna, our material girl of the '80s, the next, indescribably incompatible yet managing to coexist in the name of charity. There was enough culture shock here for an assortment of generations, and that in itself had a kind of communally cohesive effect. We are united by our incredulity at one another's musical tastes, and by our dismay at how old and fat Crosby, Stills and Nash have become.

More blast than bust, though it was a close call at times, the event on TV was hampered by technical problems (fewer than might have been expected, admittedly) and quirky editorial judgments on the part of whoever manned the controls.

A major problem was that there were three versions of the event being aired Saturday and none was complete. MTV provided the most nearly definitive coverage but the rock-video cable network insisted on imposing its gigglingly delirious "veejays" as a drenchingly wet blanket on the proceedings. An ad hoc network of stations, including Channel 20 in Washington and Channel 13 in Baltimore, carried another daylong version of the concert that was annoyingly choppy and impaired by gaping deletions.

Finally, a radio soundtrack filled in where TV pictures occasionally failed. Someone could, and perhaps will, put all three versions together and come up with three or four solid hours of great rock and good TV. A home video version could be released, with the proceeds going to famine relief. It took a patient soul to wait out the dull stretches and sit through the flubble that often beset the two TV versions of the event on Saturday.

"This is your Woodstock, and it's long overdue," Baez told the crowd in Philadelphia early in the morning. The momentousness of Woodstock was in bringing thousands of people together via the rather primitive medium of an unused meadow. Live Aid served notice that the nature of such events has changed; why trample the grass when you can bring people together electronically? On Saturday Live Aid turned the planet into a global meadow as well as the "global jukebox" its backers promised.

Whether one is taking and terrorizing hostages from an airplane, or staging a fund-raising rock concert, television is required to get the world's attention. That's not just the nature of the age, that is the age.

Selflessness was the self-professed order of the day, with none of the performers accepting payment for participating, but selflessness was not always what came through on the air. The MTV stunt was particularly galling. During the finale to the British half of the event, staged in Wembley Stadium in London, when Paul McCartney was leading a small band of all-stars (but not reunited Beatles) through "Let It Be," the director of the MTV coverage repeatedly inserted reaction shots of the MTV veejays watching on monitors from their stage-side berth in Philadelphia.

This was just what nobody in his right mind with the possible exception of the veejays' parents wanted to see.

The song had suffered enough at that point; the first three choruses were inaudible because McCartney's microphone wasn't working. But to have ballyhooed McCartney's rare concert appearance in advance and then destroy it with frequent shots of Martha Quinn and Mark Goodman gettin' real groovy seemed a new definition of exploitative hubris.

Bob Geldof, the Boomtown Rats singer who inspired the event, got so many encomiums he seemed to be campaigning for pope. The quintessential unmade bed, he is not a particularly galvanizing appearance. Piped in by phone to a live MTV press conference held to announce the event in June, Geldof rudely complained that the other participants in the press conference were "boring me to death." This is the guy people are talking about, apparently in all seriousness, as a candidate for the Nobel Peace Prize.

Channel 20 was no slouch at high-profiling it, either, superimposing its identifying logo on the screen at least four times per hour, an intrusive promotional impertinence. The ad hoc network coverage included extremely frequent commercial interruptions, and even if money was being raised for famine relief by the commercials, as was claimed, it seemed odd that they had to be so numerous, and that virtually no stage performance was deemed immune from being interrupted for them. Except maybe the Boomtown Rats.

Some viewers might have been distressed, or at least perplexed, as well, that a telethon for famine relief was punctuated with plentiful land-of-plenty spiels for chicken nuggets, candy bars, fast-food joints and a potato chip containing, oh miracle of the ages, its own sour cream dip.

The McCartney finale, meanwhile, wasn't even seen on the ad hoc network, which also bypassed or short-changed many of the other acts on the program, including a collector's item duet by Elton John and George Michael of the currently big-selling group Wham! That was left in midword so that Ashford and Simpson and Teddy Pendergrass could be picked up, also in midword, back in the States. What was needed here was some of that old Roone Arledge razzle-dazzle and simple videotape finesse; if two strong acts were performing at the same time in the two main concert locations, one could have been taped and played back when the other was concluded.

Live Aid lacked "Wide World of Sports" know-how, which was a pity, since this was Wide World of World.

Quinn, in a tipsily gigglesome state, and Goodman, bubbling to beat the bands, joined the other MTV veejays to shatter the blither meter with their achingly facile blab (they exchanged inanities about a previous act while REO Speedwagon, those hardworking lads, was singing its big hit "I Can't Fight This Feeling"), but they were given competition by the string of ditzes hired to host the ad hoc network version, starting off with a woozily distracted George Segal, smiling the way Woody Allen smiled when he stepped out of the orgasmatron in "Sleeper." Marilyn McCoo maintained brave professionalism at his side.

Later they were replaced by two of our nation's intellectual elite, Kenny Loggins and Sheena Easton. "There was a very moving moment a few minutes ago," Loggins told viewers after the action shifted, too late, back to Ashford, Simpson and Pendergrass in Philadelphia. Of course you haven't really lived until you've heard Sheena Easton hold forth on the subject of diarrhea in the Third World.

"This is not more-of-the-same that we've been seeing on television all our lives," Loggins said later. "This is now."

Most noticeable of the commercials that were repeated throughout the day was a special theme commercial thrown together in less than a week by the N.W. Ayer agency for AT&T Communications. Photographs of the victims of famine were melded together while new lyrics to the company's old "Reach Out" theme were sung: "Reach out, reach out and touch someone/ Someone whose only hope is you . . . " It was very effective, at least the first 20 times or so.

Less charitably minded was the Lionel Richie spot for Pepsi-Cola informing viewers they were part of a new generation (newer than the one in April, when the commercial first aired?). Richie, mercifully absent from most of the program, appeared at the very end in Philadelphia. One couldn't help thinking that this appearance had to be worth a million bucks to Pepsi after the rigorous reinforcement of its Richie ties all through the day.

In terms of sustaining an aura of visual excitement, the concert portions were not very well directed. Shots were changed at regular intervals with little regard to what was happening on stage, though once, probably by accident, a director went to an overhead shot just as Elton John, in "Rocket Man," was singing, "I miss the Earth so much."

The audience in England seemed demonstrably more enthusiastic and responsive than the one in Philadelphia, never more so perhaps than during the appearance of Queen and its explosively charismatic lead singer, Freddie Mercury. Obligingly and with little coaching, the crowd turned into a huge sea of extras for what amounted to a re-creation of Queen's stunning "Radio Ga-Ga" video, with vast waves of arms clapping or swaying in unison. Unprompted, they later sang refrains like "We will, we will, rock you" and did an undulating mob ballet on "We Are the Champions."

In terms of presence, that tantalizing scamp Madonna seemed a champion herself, gamboling through a Vegassy turn that had a welcome formal professionalism after so many groups who merely stumbled and staggered about the stage. Bette Midler, no petite pomme de terre herself, introduced Madonna as "a woman who pulled herself up by her bra straps, and has been known to let them down occasionally."

The existence and publication of nude photographs of Madonna became meganews last week, a story pursued by the press with the kind of heedlessly obsessive zeal it showed for the hostage crisis or would later show for the president's polyp. Madonna told the crowd she would not remove the cute Sgt. Pepper jacket she wore, or remove anything else, in spite of the intense heat. "They might hold it against me 10 years from now," she said.

Madonna seems more than the latest blip on the celebrity horizon. Her fragility and vulnerability recall Marilyn Monroe as much as her celebrated figure does.

Music being a very subjective matter, and rock stars having their own passionate constituencies, proclaiming what were the highlights of Live Aid is risky, and perhaps monkey, business. But in terms of how music and performance translated into television, a high was hit very early in the proceedings when Sting stood on the stage at Wembley and with saxophone accompaniment by Branford Marsalis, sang a starkly plaintive and eloquent "Roxanne." This was immediately followed by Phil Collins, who did with "Against All Odds" what only Phil Collins can do with "Against All Odds." Collins hopped a Concorde for America after that and MTV cameras dutifully documented his arrival at JFK Airport in New York.

Following "Message in a Bottle" by Sting, Collins joined him, with Marsalis, for the Police hit "Every Breath You Take." It was one of the few examples of really exquisite musicianship during the whole day. Later, there were such notable standouts as B.B. King, live from Holland, a venerable pillar of blues dignity; the dauntingly stylish Sade; and the hilarious sexual overstatement of Tina Turner teamed with Mick Jagger near the show's end on ABC prime time. During the day, it sometimes seemed the ad hoc network was forgoing certifiable highlights so they could be saved for ABC that night, but the ABC presentation was by no means comprehensive.

Bob Dylan seemed sadly out of sync, and he's beginning to look like Tiny Tim. But earlier, within the space of an hour, one could see two rock milestones, "Layla" and "Stairway to Heaven," performed by the original artists, Eric Clapton and Led Zeppelin, and it would have been awfully hard not to be impressed. Imagine what a knee-slapping time the gang from "The Big Chill" would have had gathered around a television set for that one.

Live Aid had additional significance. It served to mark the arrival in an inarguably big way of stereophonic television. Channel 20, which recently began stereocasting to little notice, aired the daylong coverage in stereo sound that, despite such interference as a marauding hum from England (and occasional unnerving mike feedback during Elton John's set) was strikingly good.

As fitfully fabulous as the bicontinental concerts were, the commentary between acts smacked heavily of self-congratulation, and there is every reason to fear that will be righteously perpetuated in the days and perhaps weeks ahead. The spirit of the '60s will be declared reborn, but you can't really hear it in the lyrics to "We Are the World," which note with self-preservationism "There's a choice we're making; we're saving our own lives," or, even worse, in the observation about starving children that is part of the British faminist ditty "Feed the World": "Well tonight, thank God it's them instead of you." How humanitarian can you get?

Television, and the communications satellite, enabled the event to be truly global. Every now and then the stars and the jabberjockeys would shut up about the great significance of it all and, on one's own, a viewer might suddenly have felt the impact of that significance, perhaps because a singer or a song stirred up a certain emotional connection, as when Sting sang of his message in a bottle, actually going out to outer space and back to Earth again. At such moments, Live Aid surmounted and transcended the very technology that made it possible and transmitted a gratifyingly heightened sense of human community. It was a feel-good party for the world, and for a while at least, it worked.