The reason why you lift the dog up is that in order to get the dog to be submissive, he needs to be put into a prone position with it's neck exposed. It plays on their instincts and will help achieve a better bond with the animal. If you just try to force the dog to roll over you could end up breaking one of the dogs legs. Have you ever tried to roll an extremely strong puppy over? Very tough to do without exerting force that feels as though it will harm the animal. He's not slamming the dog down like a wrestler. If he's doing it too rough, it could be due to the dog just being too heavy and him getting tired of lifting but unfortunately you can't keep starting and stopping because the dog will get mixed signals. Positive reinforcement does not always work with dogs and then they are large and powerful working dogs, something like this will obviously look more alarming than if they were doing the same to a pug (though of course will not be trained to be a police dog). I swear to you that I love dogs and treat them very well. I once needed to do this to my Rottweiller when she pee's on the floor. I couldn't push her nose down because she was just too strong. She needed to be flipped over so she could be given the appropriate negative reinforcement. Some dogs need it, some dogs don't.