I completely disagree. This cop didn't waste time telling that man that he was under arrest and then didn't waste time warning him that he was about to fire the taser, either. Just shot him and thought it was funny.
It is very clear from the tape that this young man and his family pulled over immediately and furnished the documents quickly. The young man's only crime was believing that the police officer was honestly mistaken about the situation and that he could discuss it with him like an equal.
Silly guy, right? After all, we should all be treated like dope-smuggling escaped felon gang-bangers, just because we aren't cops.
So the officer is suppoosed to somehow magically know that this isn't an escaped felon, just waiting for a chance to pop a cap in his behind?
In todays world a LEO can't afford to take the chance.
Say what you will of the officers actions but, again IMO, he was justified with the actions that had already happened.