Correct upper right arm and right wrist position at top of backswing

I’m unclear on the preferred right arm position at top of backswing from “A simple tip for great ball striking” video. At the top of the backswing, how much should the upper right arm fold in and detach from the torso? Can you recommend a video showing this in detail from a couple of viewpoints?

Also, I’m unclear on the preferred wrist positions at the top of the backswing. To me, your right wrist appears cupped and the left wrist appears flat. Am I correct? If so, I find it difficult to get my right wrist to cup naturally at the top of the backswing. Any tips to do this?

Thanks!