Larry Lessig recounts the story of a perfect example of the inadequacy of fair use: a political (anti-Obama) parody video was taken down on the basis of a ridiculous copyright claim. Like Lessig, I don't agree with the video, but I do agree with the right of the maker to post it, and I believe that if copyright can be used to suppress political remix in election seasons, it makes us all worse off.
That it was suppressed, however, is a feature/bug of current copyright law. The video is making a powerful (if wrong, imho) argument about the source of responsibility for this financial mess. It uses text (sparsely placed, as is my own style too, though the author needs a better font), images of newspaper articles, pictures of the candidates, and clips from television, all to the end of making the political argument.
That part's relatively easy from a fair use perspective. What isn't is the music. As is increasingly the style for amateur (in the good sense of the word -- people who do what they do for the love of what they do and not for the money) remix: music is attached to parts of the video to give it a special boost in social meaning, or significance. The cultural reference enhances the political. It becomes part of the story.
So, for example. when describing how Fannie and Freddie gave low interest and no interest loans, the music is Dire Straits "Money for Nothing." And when talking about the speculation, Talking Head's "Burning down the house." When talking about the influence of money inside the campaigns, AcDc "Money Talks." And when talking about how "it ends now" if (as the author but not this author hopes) Obama is defeated, the music is "Survivor - Eye of the Tiger." In each case, the music amplifies the message in powerfully and socially relevant way.