How does it differentiate between normal ranting and hate speech? How is hate speech classified in the US vs Saudi Arabia? How does it tell the difference between someone asking a child innocent questions and asking them sexually-related questions on camera? Does the algorithm get trained to flag videos about depression that might lead to suicide, or does it say they're supporting getting help FOR depression and leave the video?

What about subjects that aren't already in the corpus of "flag these naughty things"? You still have to get a human to look at those; most likely a data scientist who knows what the algorithm is doing and what needs to be done to correct the training. Machine learning as-is will not get us there, so in the meantime the only option is moderation by people described in the article. It can be outsourced elsewhere, but it's just shifting the responsibility to a different subset of people.