Originally Posted by cdhuben
I would guess a 1 GB flash memory could hold enough data for 5 - 10 minutes of video if it was constantly being overwritten.
More than that. I have an ATC-1000, with a 1GB flash card in it. It's writing 640x480 at 15 FPS (sufficent for such uses) and it gets over an hour per card. If you insisted on 30FPS you could cut that in half.
It's writing MJPEG, which is nice because every frame is a key frame, and you can edit out pieces of video losslessly. If you used a motion-based codec it should take even less space but need more CPU to encode the video.