The real "trick" was finding anything remotely interesting to do in 640x480. The only reason it even happened was because I happened to have a GL2 on hand and I was a bored college freshman. The main reason it worked is because the computer doesn't have to do both the capturing and whatever work you want to capture at the same time.

Even then, it doesn't really look very good. Here's my recording. (Anything else you see on my channel, you've done at your own risk. I'm exceedingly boring on camera.)

Mac OS X 10.6 or newer introduced screen recording. I've tried that, too. It's okay and modern Macs are fast enough to do it without too much effort. I haven't tried any really long screen records, so I'm not 100% sure what would happen if you started recording and let it run for a long time.