You are looking like you are falling to the left fairly regularly, I have had those knee problems so that might be an explanation. As far as your swing, a little pull behind the back when playing that deep is normal. You have to otherwise you can't get the ball out to the right. You have a little bit more than you want primarily because you have your wrist over cupped through out your swing. I wouldn't recommend breaking your wrist but that much cupping is actually lowering your accuracy and RPM. You really want to be looking for a relaxed swing which is not possible with your elbow bent. Also, at your release try to think more about rolling the ball instead of throwing it. That will help add RPM that you might lose straightening your wrist. There is a really good bowler in you, I can see flashes of it in your game. That is the only reason I was splitting hairs here. All around pretty good. Keep it up.
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Always be sincere, even when you don't mean it
The Cell Pimp