Everyone is biased, whether you realise that or not, and the ones that can't see or understand that are in more trouble than most. Balanced documentaries are an extremely rare event because the very reason they exist is to put forward a particular argument. I watch dozens a year on a multitude of topics and hardly ever come across a fair minded effort. That doesn't make them any weaker for that reason. And of course, they don't have to be fair and balanced, because the field is upon to anyone to provide a counter argument. So if somebody subscribes to one source or channel of information to assimilate an understanding of the world around them, then they will be all the poorer.