Dude who is out of his car just stands there like "what are you going to do?" when the other guy is waving his gun at him and firing into the air. Like "Are you really going to shoot me and go to prison over this, dumbass? With everyone around discretely taking video?" Also likely dashcams picked up some of the incident.
Don't know the whole situation, but with a gun pointed at you, you'd be an idiot to think he wouldn't kill you on camera. Either he had a good reason to pull it out, or he didn't, is an idiot and wouldn't think of the consequences.
You seem to be implying he didn't have it stashed while driving around. I didn't see proof of that, but its perfectly legal to drive with a gun in your car.