Get out the Reese's Pieces: "E.T. -- The Extra-Terrestrial" will make its long-awaited home video debut this fall in a limited-time offer, probably priced at $30 or less. MCA Home Video has yet to firm up the price or release date for the tape, and wouldn't be talking about it at all if a New York Times story on MCA last week hadn't mentioned that plans for the tape's release were underway.

"We got caught a little short," admits MCA Home Entertainment Group President Gene Giaquinto. "We haven't finalized plans yet, but with an asset like this you can't keep the rumors flying, so we had to say something."

The 1982 film has been virtually unseen by the public since its 1985 rerelease. Director Steven Spielberg was on record as saying he never wanted the film to come out on video, but Giaquinto says that after the director learned of the "very, very special" plans for the tape, "he finally did give his blessing to it." Giaquinto's plans may sound mysterious, but his goals are anything but -- he predicts "without question" that "E.T." will become the biggest-selling videocassette ever. That should come as no surprise: With worldwide ticket sales of more than $700 million, "E.T." ranks as the highest-grossing movie in history. Toys Children Watch

Child's play is serious business at the International Toy Fair, the annual trade show now being staged in New York. The fair gives toy retailers their first look at the year's candidates for the coveted slots under the Christmas tree (decorations for which are also on display). It's also the first look at the year's children's videocassettes, and while each Toy Fair brings a greater emphasis on toys that you watch, every year at least one manufacturer tries to come up with the formula that will give children the chance to interact with their TV screens.

Last year Mattel came up with dolls that moved in response to inaudible signals emitted by cartoon tapes; this year's offering (slated for a fall arrival) comes from the venerable View Master Co., whose View-Master Video System includes a special VCR add-on and tailor-made tapes featuring the Muppets, Disney characters and other licensed entities. By manipulating a joystick on a hand-held remote, children who play the tapes on VCRs that are hooked up to the $120 device will be able to affect the outcome of the stories on the screen -- by answering questions asked by the characters, or by directing the machine to play certain portions of the tape. "Imagine actually communicating with Big Bird, Mickey Mouse or Kermit," says marketing VP David Shapiro. "TV viewing will never be the same."

Other children's video developments at the fair include the formation of the Fisher-Price video label (due this fall), the most substantial direct involvement in the video business by a major toy company. The line will be distributed by Hi-Tops Video, which has more fun on tap for April, when it will begin distributing tapes of back episodes of the Saturday morning CBS series "Pee-wee's Playhouse." The level of viewer involvement with those cassettes (two half-hour episodes at $14.95 each and a three-episode rental-market tape priced at $79.95) will depend on whether young viewers take Pee-wee's scream-along secret words to heart -- and voice. Verse and Perverse

Peter Brook, director of "The Mahabarata," isn't especially known for his motion picture work, but in 1971 he did adapt his Royal Shakespeare Company production of "King Lear" for the movies, and in so doing created the first big-screen adaptation of Shakespeare's greatest tragedy. The film, with Paul Scofield in the title role, comes to video this week priced at $19.98, along with the 1968 film of Peter Hall's RSC "A Midsummer Night's Dream," starring Diana Rigg. Both are part of Warner Home Video's latest 28-title price promotion, which also brings the video debut of the X-rated 1974 cartoon "The Nine Lives of Fritz the Cat"; the 1972 "Fritz the Cat," to which this was the sequel, will also be discounted for a limited time. Redskins Wrap Session

Who says the party has to end? Fox Hills and NFL Films Video will premiere their video of the Redskins' season highlights Tuesday night at 8 at a free screening that will be held, appropriately, at Champions in Georgetown. A few lucky fans will win free copies of the $19.95 tape, which arrives in video stores that day.