What do you mean? He always seems quite unbiased and I believe he has other people do some research as well.
I don't have any specific examples to cite (as I haven't watched crash course in some time), but I can assure you it is there.
Some issues I have with the series:
-Misquoting quotes
-Misinformation (this is primarily because of the very short time limit used to cover very broad topics.
-Leaning heavily on the "Noble Savage" trope
-Being overly concerned with Anti-Eurocentricism to the point of glossing over, marginalizing, or misrepresenting European history, accomplishment, and/or perspective
It's an alright source for the very basics of their topics but I would not take them much deeper than face value. They should be used as a stepping stone into the subject you are watching and I would never use any of his videos as a source for either a paper, report, or argument. As said, there are other, better history channels available (that I would be happy to provide after work if you are interested).
I make this up out of the blue but would not be surprised
If you have no reason to believe this, then please refrain from making these kind of comments. It's demeaning, undermining, and is little more than mudslinging without any ground to stand on.