Video analysis of technique in sports

I've always found video analysis of performances for technique useful as augmented feedback for the performer. Before my waterproof camera drowned, I've used it numerous times to provide feedback for people learning to do kayak braces and rolls, and also for myself when I do playboating tricks.

For example, when learning how to roll, kayakers usually do not have the fine proprioceptive sense to know how movement is generated by their body. Whether they roll up or not, they can't tell where the power comes from, whether the body or the head comes up above the water first, whether their body is perpendicular to the boat or leaning fore or aft at setup position, or even whether they managed to do the hip flick or not. In these cases, it is much easier to show them literally how they performed by reviewing the video, rather than trying to do an imitation of their performance for them to see their mistakes.

I also use it to review my own performance, like getting my friends to film me in action shooting a polo ball, so that I can see the extent of the shoulder-joint rotation in generating power. But to use video for your own feedback, you must first know what are the characteristics of good performance and technique, know which movement/limb to watch and critique, and then have adequate motor skills to adjust your technique towards the ideal example.

Now, I just need to get another waterproof camera first...