The first of NBC-TV's ""Disney Night at the Movies"": A showcase of high-profile Disney movies either not yet televised or seen in a complete one-night showing, paired together with episodes of Disney's award-winnig ""True-Life Adventures"" series. The first special opens with the 1950 TLA short, ""Beaver Valley"": Beavers at work and play mixed with clever narration and mostly comical music. The main feature is Disney's science-fiction/fantasy masterpiece, ""20,000 Leagues Under the Sea"" (1954). Three survivors of a deadly shipwreck find refuge aboard the Nautilus, a fantastic submarine thought by many to be some sort of unnatural monster. On board, Professor Arronax, his assistant, Conseil, and sailor Ned Land end up playing a cat and mouse game of escape with the Nautilus' leader, a half-crazed genius named Nemo.