Unlike Saudi Arabia, America is not some kind of police state that caters to angry mob justice. The procedure that's followed here is to prevent the police, undoubtedly the most powerful civilian members of society, from being corrupted by their power.
The purpose of the police is *not* to punish. That is the purpose of the legal system. The police have only the authority to apprehend a subject. But some force is justifiable. If a suspect refuses to cooperate in an arrest, the police can use force to incapacitate that person. If an individual fires at the police, the police can fire back at them. But once a suspect is in custody, what possible purpose could beating the cr@p out of that suspect possibly serve? From the video, it was pretty apparent that the guy was incapacitated by the police moments after he got out of his car (since they outnumbered him 20 to 1), but they went on beating him for at least a minute. Why?
Many people here seem to think that its understandable that the cops beat the guy, and therefore they should be let off. Well of course it's "understandable". But then again, most battery and assault incidents in this country would be "understandable" if you listened to the facts behind it. If someone did something mean to me, and later on in the day, I went and beat the cr@p out of him, I would face assault charges. Thankfully - unlike millitary officers - civilian police officers are not, at any time, "above the law". When they commit a vicious act of battery, regardless of the fact that they were angry, they must be held accountable for it.