"Bill Cosby in 'Aesop's Fables.' " Karl-Lorimar. $14.95. If the video revolution has a downside, this is it: The prospect that anything ever produced on film or tape, regardless of merit, can be resurrected and foisted on unsuspecting buyers. Here Karl-Lorimar tries to capitalize on Cosby's current reign as King of TV by dusting off a forgettable 1971 program that looks as if it may have been the pilot for an unsold children's series. Written by Earl Hamner before he created "The Waltons," it features a low-key Cosby as Aesop, who introduces a banal cartoon about "The Tortoise and the Hare."