In response to the above, which I wrote in some kind of delirium but I think made some good points.
Youtube has long been an echo chamber. You watch a 9/11 conspiracy theory video and it'll suggest a tonne more. Thus confirming your belief. You watch an anti-vaxxer video and the same happens. One causes zero harm to society (there will be consequences if you go into a bar full of Afghanistan vets and spout that) but social consequences. Anti-vaxxer stuff literally threatens my life as I don't get a little ill from infections, I get carted off to resus after the paramedics have called someone who can stabilise me before moving me.
Even so, I would never, ever suppress their videos or ideas. If I was obsessed with creating an algorithm for recommending similar videos I would suppress nothing. This is wrong and the curation of information and ideas is not a decision for a private company. They may not be "deleting" or "hiding" the videos but you try and find a video on Youtube that's in a restricted state. Unless you have a direct link it may as well not exist. No search will find it and it will not appear on any feeds. It's a coward's way out so they can say "we're not deleting things" but they are just stopping anyone finding it. It's like saying "we're not burning these books" but they're locked away in an underground vault where no one will ever be able to read them unless they have a key.
The solution? Identify these "dangerous" topics (again, I want to know WHO determines they're dangerous. These Silicon Valley companies are hives of hard leftists and social justice warriors which is fine if you're on that side of things but if you're not then you'll probably find they think your content is dangerous and wrong and must be hidden) and create an algorithm to feed the opposing view to the person's feed as well. Trust the individual to absorb the information and come to a decision.
What they're saying is that people aren't capable of coming to decisions deemed rational by us, therefore we must hide any further evidence supporting their wrongthink. Y'know what'll happen? People will notice that their feeds are now devoid of what they were watching, they'll think that there's some reason for this (such as their views being right and the only way to counter them is to suppress them rather than fighting them) and it'll BREED the conspiracy theories. Because you should only need to suppress a set of ideas if they can't be fought in the open marketplace of ideas.
And yes, you're there thinking "well, it's only the anti-vaxxers, they're definitely wrong". Yep. For now. Once these systems are in place I guarantee you that 12 months from now people with perfectly reasonable ideas will have them quashed by Youtube because someone didn't agree. It happens EVERY TIME.
Freedom of speech, expression, seeking and imparting information and ideas through any form of media, regardless of frontiers has been a cornerstone of international law, starting from article 19 of the Universal Declaration of Human Rights and has been copied and pasted into other international laws. I hate the utter rubbish anti-vaxxers spout but I will defend their right to say it, as long as I have the right to tell them why they are wrong. That way we educate and change minds. By simply hiding things, we just give them a reason to believe they're right and we don't have the facts with which to fight them.
Change the algorithm so it ALSO (no exclusively) feeds them the alternative viewpoint. Otherwise they'll see nothing in their feed of interest and just search manually anyway.