Teachable Moments: Where is the line?

http://www.youtube.com/watch?v=DP2Dp0rRUw4&OK, I've coached high school sports, I see what he's doing here. I get it and I applaud the coach for doing something that the student will always remember. Certainly, on this trip the coach has clearly communicated that he's in charge!But this video also begs the question: What is the difference between a teachable moment and public humiliation?For some reason this doesn't seem like it's over the line. But it feels really close!