Ah, H.264. The current darling of video codecs. I don't have QuickTime Pro, so this is H.264 Low Profile.
H.264, high quality.
Uh-oh. Already artifacting heavily.
Incidentally, I did Best also, and it didn't look any better. For the Doubting Thomases among you:
H.264, best quality.
Like I said: No better. But it is bigger. So you don't need to worry about H.264 Best.
H.264, medium quality.
Mostly doesn't look that different from High/Best, but look at xterm. It's groaning. (Notice the word “Plists” above the iShowU bug.)
H.264, low quality.
Looks like a VHS capture at this point.
H.264 Medium (unless you use a similar xterm color scheme to mine, in which case High)