Well, I'm just going to throw out there that you would be better off posting this on a video forum. I'm sure you'll get good answers here, but most of us are strictly still photographers.
In my opinion, your best bet for better (MUCH BETTER!) video quality, would be to go get a go pro helmet cam. They run $180-300 depending on which one you get, but they put out really great HD video, and are pretty small and light.
The problem I see is that you won't be able to eliminate the shake in it, unless you could add some kind of stabilization system for the camera, but those can get super expensive and heavy.