The dispute is about DVD encryption. Basically, it’s legal for documentary filmmakers to use snippets of copyrighted films in their own movies, under a provision of copyright law known as fair use. The weird part, though, is that the Digital Millennium Copyright Act (DMCA) of 1998 makes it illegal for them to break the encryption on DVDs in order to get at the video.
If you’re showing film clips in class, you’ll probably want to make a DVD clip reel — your own DVD with the clips you want preloaded on it. That way you can avoid the frenzied scan through chapter titles and the awkward dead time while you wait for the menu sequence to load. And making a clip reel is easier than you think.
(If you’d like, you can download a PDF manual of this guide.)