I suspect that enough differences may exist between liberal and conservative subpopulations that there may be differences in the media they prefer to produce an

I suspect that enough differences may exist between liberal and conservative subpopulations that there may be differences in the media they prefer to produce and consume. For example, talk radio is much more popular for the right wing than the left. Left wing commentators and performers have occasionally tried to break into talk radio and they generally don't accrue an audience. Given that, I wouldn't be surprised if YouTube in particular (or any one site by itself) had more right-wing extreme content than left-wing extreme content. Left-wing extreme content may exist in equal proportion overall without having much of a presence specifically on YouTube.