You know ex-CEO Michael Eisner has really left the building when a Disney DVD dares to bring back and celebrate two of his associates-turned-nemeses, Jeffrey Katzenberg and Roy E. Disney. Bonus material on The Little Mermaid: Platinum Edition (G, 83 mins., 1989) hails both these corporate outcasts as critical in revitalizing Disney's moribund animation in the late '80s. Katzenberg does eat some humble pie, however, forced to confess that he nearly succeeded in cutting ''Part of Your World'' out of the movie you know, the history-changing Howard Ashman Alan Menken show tune without which we might not have had one last golden age of cartoons, The Lion King on Broadway, or a billion-dollar Disney Princess line of merch. Other interviewees range from John Waters, delighting in how the late Divine inspired the villain Ursula, to a Hans Christian Andersen heir, recalling the storyteller's lonely last days. Not discussed: how the 2-D animation revival Mermaid heralded has pretty much died and turned to sea foam, just like Andersen's original Ariel. That's for another fairy tale.