Communication Is The Enemy.

        Usually, police brutality seems to be  a product of cops with frayed nerves and pent-up aggression. After  a days worth of verbal abuse, dealing with low lifes, and feeling in constant danger, adrenalin will rush through the blood after a perceived insult or fight. In this case, I think there is some definite anger, but I suspect the cop who struck the other cop's son was trying to prevent the story from getting out before the police officers involved in the altercation had time to filter the story. Some commenters on the thread for this video noted that camera  suspiciously pans away before the action has stopped.