Well, unless we are to assume the cop left his post as a crossing guard, randomly selected the guy and decided to ruin his day, yeah, the dude messed with a cop and then refused to comply. The result is predictable. Bang on a car, with or without a cop in it, even just a plain old Joe, and see what happens.
And, no, I an not a back the blue freak by any means.
“unless we are to assume”
We? You do, in fact, speak for yourself.
The video show the cops attacked the guy and the guy fought back. Then the video shows the cops spewing nonsense that is immediately lapped up.
You assume it was random. My guess it was payback for the previous encounter, as referenced by the spokesman.