The police are trained to react to force with force. If you continue to escalate a situation via use of more force, they will do the same.
If you continue to escalate a situation, you have no leg to stand on legally when it comes to "police brutality".
If, however, you cooperate and are a victim of an unnecessary beating, you can bet your ass you'll have enough evidence on YouTube before you're even in the back of a squad car to sue the force for a metric fucktonne of money and lose the offending officer(s) their badge.