Secondly, for the folks saying why should we allow youtube to scale beyond what it can handle, or why should we accept the 99.99% precision ?
It is because I do not see a futuristic society in which humans are doing work like "manual reviews" - to progress humanity we need to automate such manual labour so I support the fact that companies are testing the limits of automatic content moderation - and working to improve it - I see it as a win overall. Adding human reviewers would be a step in the backward direction IMO.