It looks like the guy with the gun got out of his car, which was not surrounded, and started chasing protesters (only one of whom shown was even in the street, and not directly in his way). When they chased back and surrounded him, he produced a weapon and discharged it, the police moved in on him. The first rule of self-defense is that if you start it, you are the aggressor, not the defender. The incident was avoidable from the information shown.
As a CCW holder, what I am seeing is someone who could have driven past the crowd and not been surrounded by the pro-Pali protesters. There likely is more to this story than that clip of video shows, and I have absolutely no sympathy for or with the Pro-Palestinian group, but a having a CCW or just having a firearm is no excuse for looking for trouble and provoking an avoidable incident.
Maybe that's why there were 10 or so cops drawing down on the guy.
Again, the above is comment based on the information shown in the video, and there may be other information not provided which would change that analysis.