The problem is that there's very rarely "facts" showing that race played a role in a specific incident. No cop is gonna yell out "Im doing this because you're black!" while they're beating on someone. But that doesn't mean race didn't play a role, either consciously or subconsciously. And given the overwhelming evidence that law enforcement treats black and white people differently, people are justified in thinking race may play a role in any incident where our own personal experiences tell us something is off (for example I don't know a single white person who has ever been arrested for trying to use a fake ID at a bar, let alone slammed to the pavement causing their head to bleed).
I've got a buddy who was arrested in Richmond, and had his arm broken when they were trying to cuff him (white guy). He wasn't "drunk" at the time - but it was New Year's a few years ago (this latest incident was St. Paddy's day which I'm sure didn't help the situation either). I posted above where ATF cops from this same town pulled a gun on a young white girl, and threw her in jail for 24 hours for buying bottled water. You can post situations from other towns and other states across the country, but I would think an example of another UVA student dealing with this same law enforcement department would hold more water (pardon the pun).
I'm not saying this wasn't racially motivated, but lets not immediately jump to that conclusion. It was 1 in the morning and an underage kid was attempting to get into a bar illegally on a holiday notorious for drinking. The indications are that he was drunk prior to the incident as well, so drunk in public. While I personally don't feel either should be a crime (or at least a big crime), the fact is that both are. The video also shows him attempting to resist arrest, which may have been the reason he was taken to the ground in the first place.
While on the ground he immediately starts cursing at the cops and calling them racist (so he jumps to that conclusion immediately), as do numerous media outlets with headlines like "Why did ABC Cops beat this black UVA student bloody?" and "Black UVA student beaten by police" and others.