I think the fundamental disconnect we're having, is that what you call racism I would just call racial insensitivity, or being an asshole to put it in different words.
I guess you could say that I think of racism as a true, deep level of evil. One of the three great evils of humanity along with murder and rape. And the reason I consider those to be evil is because they deny the transcendental value of human life. To that end, it's not something I toss around lightly in a serious or formal context. So from my point of view, saying that a video is racist is kind of like saying that it's murderous, or that it's rapey. It could be true of some videos but is probably not true of some random World of Warcraft video.
I see your point as to how it could be taken as mockery, and I don't think you should be forced to sit and laugh at something that you find demeaning; though I do think there can be value in learning to laugh at yourself, and more importantly laugh when confronted with the worst parts of reality, to laugh in the face of death so to speak.
So I don't completely disagree with you, I just find that for me and my long term happiness, I always want to try and rise above things that I find insulting or demeaning, though I don't always live up to that.
Edit: It would probably be fair to throw torture in there with rape, murder and racism as far as great evils go.