The color of the cop is irrelevant. The problem is cop culture. Racism makes it worse but it is plenty bad in and of itself. Again- lookup Frank Serpico sometime.
You talk about a video. I have looked at several sites and seen no video. The story the cops tell is intrinsically weird- a guy not involved with criminal activity suddenly exiting a car with a hand gun- twice. Plainsclothes cops shoot him down. I suspect you support open carry for White guys, yes?
As to the video you claim to have seen or at least have confidence exists, maybe you can give us a link or tell us how you know about it. Until then my sympathies are 100% with Black Americans and not for the immoral apologists for police violence that always find an excuse, even in some cases here, for what happened in Tulsa.