It’s possible the dog got startled by him moving his arm. I have never seen a dog get startled and then dejectedly walk over to It’s sleeping spot, and I’ve been around dogs my entire life and that is EXACTLY how a dog who has just been punished reacts. The dog yelps right as he moves his hand and he has a remote that looks identical to a shock collar remote. It is possible there are explanations for all that, it just seems incredibly unlikely to me.