I remember a while back my father was showing me a video of how a specific machine works, because he is a machinist and is into these things. It was just a normal, completely harmless "How it Works" kind of video. As the video came to an end, I said "I wonder how the comments will manage to be racial on this one." So he scrolled down, thinking I was being goofy, and sure enough the third or fourth comment was something like 'White people stole machinery from the Africans'.
Like seriously, you can't avoid it. If Charlie Manson wants proof of Helter Skelter, he doesn't need to look any further than youtube comments.