I'm wondering if that kid decided to do that on his own or was told/encouraged to do so. Some of you may remember the video of the high school player (or was it players) blind-siding a referee some years back. Wasn't it determined that he was (they were) instructed by some coach to do that?
I also notice that there was who I assume was a coach of the white team looking right at the incident, and he didn't appear to make one move to stop it, but continued to look at it from the sideline. If, as the report said, the offending player banged the kid's head repeatedly on the turf, could that not be considered assault?