Slamdunc's initial response and subsequent turnaround are insightful into what the martial arts' community's reaction would have been if this woman didn't have video to back up her statement. Many people reflexively refuse to believe women when they say they've been assaulted.
One part of that response is the just-world fallacy: "I refuse to believe that this world could be terrible enough that two guys pretend to help a friend home from the bar and instead rape her mercilessly."
Another part of that response is a pseudo-lawyer with Asberger's: "technically we don't know what happened, guys, so let's not jump to conclusions." I'm sure that was how these people viewed the OJ case, Casey Anthony, and so on.
And the rest is plain old deeply-ingrained misogyny: men get the benefit of the doubt; women need video to back up their story. Given that slamdunc is/was both LEO and Military, and his (her?) sig denounces both tits and *****, I expect this is the primary factor. (If you don't like the fact that slamdunc being LEO and military makes me jump to that conclusion, convince him (her?) not to jump to the defense of the rapist the next time the topic of sexual assault comes up.)
Note also that there are dipshits coming out of the woodwork already who are saying, despite the video, that it must have been consensual. Suffice it to say I think this is a misguided point of view.