If all you have to go on is what's on the initial video, it's not time to draw a gun. We have no way of knowing in the din of the crowded pizza joint what's actually going on, or what might have happened before this that led to it. We don't know who the other people in the joint are, nor who they're with.
If someone sees us draw a gun, figures WE'RE the bad guy, and grabs for it, everything is going to hell in a handbasket.
If one is there as a police officer of that jurisdiction, one is duty-bound to intercede and break it up. In that situation, we'll have such intermediate force tools appropriate to the task as TASER, pepper spray, and baton.
If we're a permit-holder with no enforcement authority -- and probably, in the words of a wise old cop, nothing in "that vast gray area between a kind word and a gun" -- stepping into the encounter before knowing more puts substantial quicksand under our feet.
Whatever one does in that situation, I think it would be premature to draw the gun if all one has to go on is what initially appears in the video you linked.