Kinovea (open source freeware) is really useful for analyzing your video. It can vary playback speed or advance frame by frame, lots of other tools included for measuring angles etc.
That's pretty cool stuff. I can see this being useful to a coach, or someone with some kinesiology background. It used to be that we did bike fitting by looking to align certain points of the anatomy with our contact points of the bike. I believe that kinematics will be the new way we end up fitting people. We already have equipment that can test someone's output as they move through the motion of a squat. Dialing someone's seat height to maximize the amount of time spent in the range of greatest output is something that I've always thought would be a good way to deal with bike fit. This may help in developing tools like that.