Anyway, the way I understand it is that the makers of Empire of Dreams wanted to be historically accurate, so they dug out old, pre-SE footage (with Lucas' approval).
THE VAST MAJORITY of the clips from the films in Empire of Dreams are actually from the pre-2004 DVD Special Editons, but certain specific shots that had noticable changes for the later versions (the ANH-less opening crawl, Alderaan getting blown up, the rebel fighters flying away from the Death Star before it blows up, some Cloud City shots, etc.) are taken from the the Pre-SE/OOT archives (and the quality is noticably lower).