Unnecessary force requires no translation. People will stomach only so much mistreatment before they revolt. In this video, the cop who was doing the worst hitting of the pinned prisoner with a stick runs away from the crowd first. The cop who was telling the hitter to stop is the one who ended up getting beat up by the crowd the most.
I know two different people who have been beaten up needlessly by hyped up cops. I also have a cop in my family, so I've heard both sides. The solution, obviously, is to only have police who use force appropriate to the situation.