It's not a prequel! It's not a remake! It's a "premake" -- a re-imaging of a favorite film as the product of a bygone era. In this case it's Star Wars Episode V: The Empire Strikes Back, rejiggered from footage from old serials, b-movies, and TV shows. StarWars.com has a full list of the source material for the film, remixed by youtube user "Whoiseyevan."
Creating a video like this is an admirable skill, not unlike DJs that are adept at pop song mash-ups. I certainly couldn't think of all the individual shots from old films that it would take to create something that recalls a completely different film. While I don't agree that Leslie Nielsen is the 1950s version of Mark Hamill, their retro Chewbacca is pretty spot on.
You can view the mock trailer for The Empire Strikes Back (1950) after the jump.