Although Richard Donner filmed Superman II I and Superman II simultaneously, he was let go after the premiere of the first film. Fans who demanded a Donner-restored version of Superman II were somewhat appeased in the ’80s when Warner Bros. put together an extended international TV version containing the extra Donner footage. The Restored International Cut is the result of patching togerther videotaped clips of that TV braodcast sent in from fans around the globe.
I just went to the website. The Restored International Cut has been removed at the “request” of Warner Bros. The DVD artwork is still downloadable, though.