Is that because they are black though? Without asking those people why they watched something else you are just making the assumption it was to do with their skin colour and not anything to do with the content itself.
e.g. I don't watch a lot of content with women on Youtube. Not because I have anything against women. It because the subjects I am interested in, isn't covered typically by women.
Bluntly, yes. A lot of people in the U.S. are implicitly or explicitly racist. You can see this in statistics, such as 'black-sounding' resumes consistently getting less callbacks than 'white-sounding' resumes [1].
e.g. I don't watch a lot of content with women on Youtube. Not because I have anything against women. It because the subjects I am interested in, isn't covered typically by women.