Get Hypercam 2. I know, but the watermark isn't there anymore (unless you're using Hypercam 3 (if you do see somebody using it, tell them to piss off)), making it the best screen capture software out there. It's incredibly easy to set up and use, and you can record long videos without eating up too much space on your hard drive. (And you should probably choose a better game. I'm not saying that LTTP is bad, but as I said before the latest ER, this is a very well known game, meaning that it's gonna be hard to find something new to say. This is even more of a problem when we don't know that you can deliver awesome commentary, like Ryan and Patrick for the ER.)
Thanks for the recommendation. I was going to use Hypercam originally but they don't support mac. If it's that good though, I could always just install Windows through bootcamp. Also, great advice about LTTP; I hadn't really thought about that, but you're right, it's something most gamers are familiar with.
And Fraps also looks like it's just for Windows as well. Looks more and more likely that I'll just be running bootcamp here.