Why do most swim coaches want to see video of someone from the front, from the top, and from the side, but nobody ever asks for video of someone from the rear? I would think that if the video was taken to one side, then the other, right in the swimmer's wake, you would be able to see some VERY important information. You could see the amount of the arm that is being used for the pull, you could see the upper body rotation, and the lower body rotation, and you would be able to easily see the depth of kick (as long as the person was not kicking washing machine style.)
Maybe that angle is hard to capture and see... I need to get me an underwater camera..