It is difficult to talk about this without being attacked so please do not jump to attack or call me racist. I am coming from a perspective in which my family and friends are police officers who do not have an ugly bone in their body and who do their best to help people. Here goes.
Given the state of America, with the proliferation of guns, and officers routinely getting killed for pulling people over for a traffic violation, it is see-able that the officer would be startled when someone does not follow their commands. I also think that there must be an internal belief in which race plays a role in their reaction: not that they are consciously thinking that they are shooting the guy cause he is black, but rather they react differently. When it is a person of color they think "the guy is going to kill me". And when it is a white guy who does not follow the commands, they may not always feel that fear.
I don't know what happened in this specific case before the video started or how it escalated.
But, what happens when the officer asks the person to keep his hands on the steering wheel numerous times, and instead of obeying, the driver reaches behind him? Now at that point, the officer fears for his life. Should the officer wait for the gun? By then it is too late--if there was a gun, he's dead. Why would the officer think that he is up to no good? Perhaps because he did not keep his hands where the officer could see them?
So, to solve this problem (and I agree there is a problem) we start with the stop. Many times these horrific deaths start with a traffic stop and escalate. Why is there an escalation? What exactly happens? What is the thought process of both the driver and the officer? How do we stop that escalation? Why does escalation end in death more for people of color? Dehumanizing all of law enforcement is wrong. It does not solve the problem--it sends people to their us-v-them corners.