I have only seen one video portraying a clear example of an "unarmed non-threatening black" suspect. I am glad that individual survived and I hope he recovers fully. I don't count the Castile video because it doesn't show what actually happened. I do believe that the Castile shooting was a horrible miscommunication and  misinterpretation of intentions by the officer. 

In nearly all of the other videos I've seen, I can see the level of escalation that leads to the shooting. This doesn't mean that I think the officer is in the right or that lethal force is justified in some of the videos. Passive aggressive behaviors and refusing to comply with an officer escalates the situation significantly.

Fighting an officer puts your life at risk, even defending yourself because if you disable the officer, you gain access to their weapon. This puts the officer and the public at risk, they can't allow it under any circumstances. The time to fight the police is in the courtroom, not on the streets.