My friend and I finally got video chat working (he got a new iMac), so we tried playing around with the video effects. He had no problem, but whenever I tried to open the video effects in iChat, the program would freeze. I tried reinstalling iChat from the Snow Leopard disk to no avail.
Then I found something about running iChat in 32-bit mode by changing the setting in the Get Info window. This seems to have fixed the problem! This is a little disturbing that there was no indication that this was necessary and only through Googling was I able to figure it out. Any ideas why I was crashing before and why forcing it to run in 32-bit fixes it on my older MBP?