A real quick method, but completely lacking in terms of quality, would be to use the screen recorder in QuickTime Player and then convert it with something like iMovie.
Alternatively, you could just use Fraps through Bootcamp, assuming you have a valid Windows product key.
Finally, through the power of Google, I came across Krut, a Java based screen recording program. I've never tried it as I just found it, however it promises to be a lightweight and fast program to use.