I have mixed feeling about this. It's kinda scary that YouTube could determine what is and isn't a conspiracy video. I could see videos regarding creation or young earth theory being lumped in based on Google/YouTube's views.
And furthermore... as much as I distain some of these conspiracy theories why shouldn't they have the right to display them? Don't we have the right to be stupid if we want to be?
I agree with you that there is a danger of some videos getting dumped in with the bad. This is why it is, in my opinion, wiser for them to not make any such attempts to filter out conspiracies.
YouTube is, however, as you are already aware, a privately owned website and no one has "the right" to post anything on their website. They, on the other hand, have the absolute right to put whatever limits and restriction they want on the content that they provide a platform for. The thing that'll keep it just about right, over the long term, is the fact that no one is required to visit their site or to use their platform. If they go to far, which is likely, it'll spawn more viable competition than what currently exists and, in the end, the internet will be better. I trust the free market to produce the best product at the best price.
Clete