``E.T. the Extra-Terrestrial'' soared into the stratosphere Thursday, the first day of the movie's release on videocassette. ``Nobody's buying just one,'' said Gail Boswell, manager of Tower Video. ``I had one customer come in and buy 120 cassettes. Others are buying two or three or four.'' Demand has been so great that MCA Home Video, the video's packager, has been unable to fill orders. Some retailers will receive only 75 percent of their requests. Boswell said she ordered 2,500 cassettes, expected 1,700 but received only 1,200. In any case, MCA Home Video, a subsidiary of MCA Inc., could enjoy revenues of close to $200 million from the ``E.T.'' sales. There are more than 11 million advance orders for the $24.95 video. Pepsi Cola is sponsoring a $5 ``E.T.'' rebate offer, and will promote the video in a $25 million advertising campaign. There is no Pepsi commercial on the video itself. Most movies are released within six months of their opening in movie theaters. ``E.T.,'' released in 1982, has never been shown on broadcast or cable television. The video release of the movie was delayed because Steven Spielberg, the film's director and producer, told Universal several years ago that he wanted the cassettes to be affordable. The previous low price for a major video release was last year's ``Top Gun,'' which sold for $26.95. About 3 million ``Top Gun'' cassettes were bought. ``Cinderella,'' which has sold more than 5 million copies in the last month, is priced at $26.99.