Although video is one medium talkmeister Larry King hasn't tried, his might be called "He Works Hard for the Money."

In recent days, the king of midnight radio has signed a new, five-year contract with Mutual Radio to do his nightly talk and call-in show and agreed to five nights of the same for Cable News Network, as well as guest commentary on baseball for Home Team Sports. "I'm on a roll," said King, 51, "but even though the schedule is tough, the shows aren't tough."

His Mutual agreement for the weeknight shows is reportedly worth $2 million. The package is a no-options contract (if Mutual drops King, it has to pay the remaining value) guaranteeing 12 Fridays off a year, four weeks of vacation and a new luxury car every two years.

King first joined Mutual in 1978 with 28 stations carrying his show. Now the Peabody Broadcasting Award-winner has 262 stations, including WTOP-AM (1500), and reaches 3 million to 5 million people a week. Within 90 days, his show will be heard for five hours from midnight to 5 a.m., the last hour a repeat of that morning's midnight-to-1 a.m. interview segment.

Although other networks made lucrative offers, King stayed with Mutual because of its familiarity. "I like the people," he said. "I like Jack Clements a great deal. Ron Nessen is terrific to work around. And while a couple of people offered more, there are other values. I would have had to move to New York, and if I went with another network they would have to get affiliates all over again." Executive Changes

David Einstein, program director for WHFS-FM (99.1) for the past 15 years, has been appointed operations manager. Meanwhile, after six days of silence due to a damaged antenna, the Annapolis station went back on the air late Friday night . . . John Watkins, news director at WTOP, was terminated last week. "As a matter of company policy, we wouldn't comment on a termination to anyone but the party concerned," said Michael Douglass, the general manager of WTOP and WTKS-FM (102.3). Kudos, Kudos

The envelope-opening yesterday morning at the American Association of University Women resounded with the names of several radio czars. Given the highest honors by the group's Metropolitan Area Mass Media Committee were Dr. Gabe Mirkin of WNTR-AM (1050) and Martin Goldsmith of WETA-FM (90.9). Also cited were Sandra Thomas of WMDO-AM (1540), Mac McGarry of WWRC-AM (980), Diane Rehm of WAMU-FM (88.5) and Frank Harden and Jackson Weaver of WMAL-AM (630). McGarry, the guest speaker, is also being honored next week by the Fordham University Club of Washington . . .

Dorcas Dessaso, the producer of the weekday "Morning Reading" on WPFW-FM (89.3), has been cited by the International Reading Association. And the Corporation for Public Broadcasting recently received the C. Stanley Potter Award from the Association of Radio Reading Services for its support of services for the blind and print-handicapped. Washington Clues

To give WCLY-FM (95.5) listeners a taste of John Dowling and Walt Starling's home town, the duo has designed a "Washington Trivia Quest." The rules and forms for this two-week scavenger hunt will be available tomorrow at the parking lots of the Hecht Co. stories in Landmark Center, Montgomery Mall and Prince George's Plaza. All participants are requested to give $5 to Children's Hospital. "One of my career goals has been to come up with a promotion no one else thought of, and we wanted to take advantage of the spring crazies," said Dowling. Program Roulette

To cure the just-before-Monday blues, WRQX-FM (107.3) has switched the phenomenally popular Rick Dees countdown show to Sundays, 7 to 11 p.m. . . . WGAY-FM (99.5) has added "To Life," a 28-minute weekly national show aimed at the 34 million women over 55, at 7 a.m. Sunday. It was developed by Washington-based producer Thea Marshall, and is underwritten by the American Association of Retired Persons. Calendar Jottings

If you're looking for the last signs of spring, you might stop by the WQRA-FM (94.3) booth at the Warrenton Spring Festival tomorrow. The station will be broadcasting from 10 a.m. to 3 p.m. from the old firehouse . . . Lisa Manning of WPKX-FM (105.9) will be doing a remote from Lustine Toyota on Route 1 in Woodbridge tomorrow from 1 to 3 p.m. She then switches to Raffles, Tysons Corner, Sunday from 4 to 8 p.m. . . .

The Preakness is on WMAL at 5:20 p.m. tomorrow . . . WPKX will be one of the sponsors of the Armed Forces Celebration Run Sunday, 8:30 a.m. at Amherst and Commerce streets in Springfield . . . Mary Cliff, the host of "Traditions" on WETA, will conduct a workshop on folk singing at the Northern Virginia Folk Festival, Sunday at 3 p.m. at the Thomas Jefferson Community Center.