From my point of view the proper way to solve this is to educate people and build up "media competence".
Who defines what a harmful video is? Such classification is always influenced by current trends, social norms and so on. What might be harmful to a child might be not even worth a shrug to an adult. What is fact today, might be laughable tomorrow and heresy the day after. Have fun navigating this.
If you think that youtube guides people on downward spirals towards extremism and is not willing to acknowledge or change it - talk to your kids and peers about it. Repeat this until they are able to decide for themselves.
But pushing some information (sort of propaganda) and hiding some information (sort of censorship) both lead down a dangerous path.
I can't put my finger right on the spot, but it seems like nuking a hurricane.