My high school PE classes have a few required proficency movements that we use video to help kids work. We video kids doing activites such as form running, A Skips, lunges and a few others. With the kids being able to watch themselves, they can see the flaws in each activity and can create a better plan of attack for improving them and reaching their proficency requirements. It's pretty simple. I usualy video on my phone and show the kids right away for instant feedback.