I love that clip. Not because I agree with him about Bush (I don't), but because he doesn't give a fuck that everybody in the room disagrees with him; in fact, I'd say he revels in it. A true badass contrarian.
I'm sorry, but: if I stood up in the middle of the day and loudly proclaimed it was midnight, would I also be a bad-ass contrarian?
The way I see the clip is: Hitchens (who I admire for a lot of things) was trying to soothe his bruised ego that he had been so colosally wrong about Bush. He was just doubling down on his massive error of judgment by continuing to support Bush. Claiming that nobody in a theater full of people he does not even know is not smarter than Bush is silly.