Here's yet another angle. That guy with the green hat at the beginning of the video - he's a lawyer from the National Lawyers' Guild who was at the protest as a legal observer. Somehow he fell and got his leg under the scooter (intentionally or unintentionally, who knows).
NYPD Assaults Legal Observer Ari Douglas - YouTube
According to another legal observer - the scooter guy was assaulted after he was already arrested. There is so much attention on this now that the truth of what really happen will come out eventually.
So funny what it says on the side of that cop car - I didn't see much respect, courtesy or professionalism.