RE: Slow motion video of string hitting arm
This CAN and DOES happen with the RIGHT draw length.The problem usaully arises when you are doing exactly what he shows in the video,heis not rotating his forearm properly and he definately looks like he is trying to make it hit his arm.
There is NO WAY to say his draw is too long from the video but you can say his form sucks,atleast the form in his arm.