Two things really stand out about Zappa in this clip: one, his utter contempt for John Lofton from minute one. It's not like he grows to hate Lofton throughout the segment; he refuses to even look at him from the beginning. And two, Zappa's meticulous preparation for the show. You just couldn't spring a tough question on this guy. Watch toward the end when Robert Novak brings up the teenaged protesters outside the Annapolis courthouse during Zappa's testimony. Not only does Zappa know exactly who they are and where they came from, he cites specific examples of absurdity from their reactionary pastor's literature.
I've said it before, I'll no doubt say it again: God bless YouTube. Think about it: somebody taped this twenty years ago, kept the tape, dug it out, digitised it, and uploaded here for your edification and mine.