Those were the days my friend/ We thought they'd never end."" Mary Hopkins' lament seems an appropriate epitaph for the moguls resurrected with a certain splendor here. Mr. Zierold's usual painstaking research reveals, for instance, that Gone With the Wind was, in part, an ""extraordinary act of revenge"" executed by David Selznick, Jr. to get back at the men who had helped destroy his father, the flamboyant Selznick, Sr. who ""never went to a movie if he could help it."" Then there was ""Uncle Carl"" Laemmle and his wild recruiting methods--""whatever the job is, you fit it like a glove""; Sam and his ""Goldwynisms,""--""Our comedies are not to be laughed at""; the kind Jesse Lasky versus the ""deliberately uncouth and vulgar"" Harry Cohn, and the clownish Jack Warner who would ""rather tell a bad joke than make a good movie."" The concentration is on the personalities rather than the intricacies of Czar-dom and this is entertainment rather than comment. As such, who knows? The Moguls might make a movie.