This is the fourth or fifth reworked version of this scene from Downfall that I've seen; as Diane says, there are tons of them out there.

I think it's hilarious, precisely because it trivialises Hitler - it turns one of the most evil men of the twentieth century into a shouty man throwing a strop over not very much. To quote from this blog post*, "We confront fascism in the same way we confront every threat to our freedom and our way of life: We point and laugh at it."

And, obviously, I don't think it's a slur on Joan C. If there's anyone reading this who really hates SOH, really loves Bellowhead, doesn't have much of a sense of humour and really liked that bit with the girl who gets her kit off, then perhaps that video is a bit of a dig at you, sir. But mostly I think it's just anti-people taking things too seriously and getting worked up over not very much - and of course anti-Nazi.

*That post, incidentally, accompanied a version of the film in which Hitler's outraged because his BNP membership has been leaked.