i have used a video camera to help explain to some people that they are flinching,,,it is way better than arguing with them,,,, had one guy,, i tried to tell him to keep his head down and follow through with the shot ,,he didn't believe me SO i got out the trusty camcorder and the first thing he said to me was,,,i can't believe i was doing that
even if you think you are doing everything right,, it won't do any harm to watch yourself,,, you might be surprised at the stuff you see
just set it up on a tripod and for get about it,,, i like to have it at 90* to the shooter
my .02
ocharry