maybe recordmydesktop - but I seem to recall it supports only Ogg codecs...
BTW, I'm on Linux, but the above tools might work on OS X too.
Haven't folowed this entire thread but also want to mention Yukon on Linux works for recording Gem output. Site seems to be down at the moment http://www.neopsis.com/projects/yukon/ . Also a good list of screen capture tools for Linux here. I've also used Istanbul. http://linuxmafia.com/faq/Apps/desktop-video-capture.html Jim