That cop is too afraid to be a cop. Even from the shitty body camera view I could see the guy was wearing earbuds and the wire attached to an Ipad or something. It was obvious the guy was listening to music. He probably didn't hear the cops orders and when he reached into his pocket to turn off the Ipad the cop flipped out and thought he was reaching for a gun and shot him.
That cop is too stupid and too fearful to be a cop.