I'd say it's because the unemployment rate among blacks is high, so they don't have to get it for their jobs at the same rate. They are also poorer, so they do

I'd say it's because the unemployment rate among blacks is high, so they don't have to get it for their jobs at the same rate. They are also poorer, so they don't get it to travel, or go do other rich people stuff. It's probably as simple as that. Also, from what I've seen, anti-vax videos are popular on WorldstarHipHop.com and other black culture venues. They often have very little censorship compared to YouTube.