So call the cops. Don’t shoot him.
I very politely suggest that you get your eyes checked. I watched the video 25 times. The black guy ran at least 14 feet at the guy with the shotgun before contact was made. The autopsy revealed that the first gunshot wound went through the black guy’s palm, indicating that he had a hand on the shotgun when it was first fired. For the life of me, I do not understand your point.