The more I think about this, the more I think the cop's own inept handling of the situation has lead to this.
Over-reaction? to a grooms defense of his bride, the best day of his life and obviously also under the influence, chased without backup 2 blocks (hence no site of bride), worst police\security guard\middle aged power tripper handcuff attempt balls up, caught on film....
No one was dying when the victim ran off, the unsupported police officer could easily have just got details from the bride and picked the suspect up later with backup, if it was deemed necessary.
His own actions blew the situation out of order, his admittance that he was puffing after the run and lame attempt to subjugate and temper the arrest , lead to his knee-jerk plan B shoot to kill!...
Gee, I don't know but seems to me, the cop made a mountain out of a mole hill, and instead of moderating justice, escalated the mood, culminating in his paranoid, terminal shooting of essentially, an innocent man.
All I can say, is I'm glad I don't live in the US of A.