I'm going to Monday morning quarterback this incident on the grounds that I've done law enforcement directly for 3+ years as a Military Policeman (21+ years of total Army Reserve time as an MP after that).
First, the officer seemed pretty damned agitated at the point that the video started. Why? He's got almost a complete tactical advantage in that situation. Driver has to make some pretty concerted efforts to draw weapon giving the officer plenty of reaction time to seek cover, etc. Why is he so fucking scared/intimidated of this one guy with girlfriend and child in the car who also disclosed that he was a concealed carry person?
Second, the driver's field of view/shot picture is almost exclusively in the area of the officer's body armor (assuming he's wearing it, which why wouldn't you be if you're this scared of a confrontation). Why wear fucking body armor if you're so afraid to use it that you just shoot first all the time? Yeah, I'm sure getting shot in the vest fucking hurts, but training and adrenaline are there for a reason.
Finally, what the fuck is up with these officers shooting people and then simply standing there watching these people bleed out and die? WTF?! You shoot someone to incapacitate them and control a deadly situation, then you should immediately transition to completely eliminating the threat (AKA, take the gun, knife, etc., away) and then treating the injured. This asshole literally appears to have just stood there, gun still pointing at the victim, the girlfriend, and the kid in the back seat watching this guy die. Fuck, even Soldiers are taught that if you shoot a bad guy and eliminate the threat, you do your best to save the life.
This shooting seems nonsensical, like many of them are lately, and callously idiotic. Even if he would have shot the guy and dragged him out of the car and begun medical aid he might have helped the situation not appear what it is now, total disregard for human life.
Guys like this police officer I suspect are the ones that go home and watch fucking YouTube videos over and over again of those shootouts on traffic stops and then just hope for their chance at glory. In fact, they should ask as part of the interview process "How many times on average do you think officers get into deadly altercations in this municipality?" and if the answer is grossly off from the real statistics, that should be an indicator of a problem right up front.