It's kinda funny to me.
Driver shows bad judgment handling his car with poor merging onto the freeway.
Then you see same driver with questionable judgment now has a gun too?
Do you drive the same with or without your gun? 
What if you stayed in your car and endure the guy yelling until the light changed.
While at the same time you shoot him in the head with your cellphone video...
just knowing he is being recorded might help to not escalate the confrontation.
Maybe a cop might be interested in the video evidence as proof of road rage?
I don't pick fights with anyone on the road, you can't tell who is driving around with a gun in his lap.