Many people didn't really want to see that video. They wanted to believe Rice was attacked by Palmer and did something to warrant being punched in the face. From the moment part of the video became public over the summer until Monday morning, it was easy to put some blame on Janay Palmer.
The woman always gets the burden of proof and the burden of pain. The woman is always cast as the gold digger, the mentally imbalanced stalker, the inappropriate dresser. The woman is always the provocateur.---from Culture of Blaming the Victim
When it takes video evidence to get the public to take abuse seriously, the power is in the hands of the people who have the videos — and decide whether or not to release them.
Without documentation, the victim's and aggressor's accounts become a "he said, she said" — and we know from media studies that people are more likely to believe accounts that confirm their prejudices. If people tend to side with the person they already know, like or trust — in this case, the star player — video evidence becomes one of the only things that can break that impasse.
---from The People Who Have the Footage Have the Power