There is no context necessary.
Most likely this cop went out of line. PERIOD
The woman is cuffed.
What you're looking for is an excuse or explanation why the pig couldn't control himself, acted totally unprofessional and abused his powers.
There is no justification for this and he should be punished.
They have rules and laws to follow too.
He deserves no sympathy or understanding.
Neither do the bootlickers of authoritarian violence who want to excuse this despicable behavior.

let's not play judge based on a couple of seconds of contextless video.

Why not? Describe a situation where that behaviour is justified.

me after a 2 second clip without context:

I've seen enough, I'm calling it