By way of the EFF: a concise overview of just how much of a pain in the ass it is to follow proper fair use provisions when remixing a scene from a movie. EFF Chairman Brad Templeton did a subtitles remix of that Hitler-ranting-at-everyone scene from the movie Downfall, with Hitler as a producer (and apparently affiliated with the MPAA). (Such remixes have frequently been subject to DMCA takedown notices on YouTube.) In order to make sure he was 100% square with the DMCA, Templeton had to order a Region 2 copy of the DVD in order to export video without subtitles through the analog hole, then reimport it (over S-video) before adding his own subtitles.

It certainly shows how much of a pain in the ass it is to jump through all the legal hoops, and how the process could be streamlined. Oh, and the parody video is really funny; you should go watch it (at the link above).