Recut, Reframe, Recycle: Quoting Copyrighted Material in User-Generated Video from American University's School of Communication looks to be an understandable guide to what all our wanna-be Ken Burns re-mixers can and can't do with copyrighted material in their own videos. There is a link to a good video clip from the Chronicle for Higher Ed on the page as well.
The basic idea here is that "fair use" is broader than usually interpreted, especially in the areas of parody and criticism. There is a great list of examples in a variety of categories of fair use, including Satire and Parody, Negative or Critical Commentary, Positive Commentary, and Quoting in Order to Start a Discussion.
Maybe it's time we started teaching kids more about what they CAN do with copyrighted material than what they CAN'T do with it if we want avoid raising a bunch of scofflaws?
(Thanks to Bill DeJohn at U of M's Minitex for the head's up.