[supercat]

Even a Weird Al Yankovic song parody is practically untouchable; add yet another layer for political free speech.

I wouldn't expect that to be the case, as music and lyrics are in some cases regarded separately at copyright law. As such, because Weird Al uses other people's music essentially verbatum, I'd expect that he'd have to pay for that. If he were to rework the tunes so as to be recognizable parody versions, then he wouldn't have to pay.

[RightWingAtheist]

Actually, he doesn't have to pay anything, but he always asks the original artist's permission before he does the parody, and his band records a new accompanying music track (if he sampled the original music, then he would probably have to pay). A running Weird Al joke is that he continually takes shots at Prince for never giving him permission to parody his songs.