Rick is unique. I took Rick's class, and wouldn't trade the experience for anything in the world.
I believe his string hand is so relaxed that it just flops when he shoots the bow. I don't think his string forearm moves at all.
Rick shoots with a dead release (his hand doesn't move back). Since the forces have to go somewhere, his hand flops. Maybe?
I have since learned to shoot with a dynamic release, where my hand moves back towards my neck if everything goes as it should. This seems easier for a mere mortal, such as me, to control.