Feel super bad for the cops here. They get called in, go through the stress of walking into an unknown situation, react the best they can while keeping as many people safe as possible, and still get shit on for doing their job. When a cop gets a call about a shooting that is happening, would y'all rather he walks up and knocks on the door politely and asks of someone is getting murdered? These dudes walk willingly into a potential firefight for us and all we do is bitch about it. Come on guys.
I don't think it's unreasonable to expect people who are supposed to be experts at handling these situations to remain calm and do what is necessary, rather than flipping out on someone who is already 100% compliant the moment they enter the room (and then continuing to disrespect him when he's already cuffed and kneeling on the ground). There is a middle ground between "knocking on the door politely" and getting over-the-top aggro like these guys.