The cop had no right to pull him over, from the looks of it, his License plate was not obstructed. This was an unlawful arrest, and the cop DID make up the charge. The guy getting arrested had the right to stand up and disagree because the cop was literally lying to his face, on camera. There was no criminal offense committed, so there was no reason for the cop to pull him over/arrest him.
Also, when the guy tried to talk and they straight up told him to shut up, that was something that is not really "okay" because they had yet to read him his rights, so he did not have to remain silent. The License plate was in a spot where it was meant to be put, though the rider could have had a mount for it so that it would be sticking out vertically, it was really up to him whether he had that or not. This was an arrest that was pretty much just made up.