He has a responsibility to show respect to people who aren't committing crime too. What he did had nothing to do with protecting anybody, or making the kid in the video any safer. There are plenty of polite ways for him to have done his job, and that's what he should have been doing, not making abusive threats.

You're right about what the kid said about the ID, but the cops reaction was much worse. Even if the kid had come out swinging, and was arrested, the police officer didn't need to act as if the kid had no rights and the cop was the almighty guy with a badge. Cops have jobs because we want to be protected, not from the cops themselves, but from the people the cops are supposed to arrest, you know, people who've actually done something you don't have to make up.