300 hours of video are uploaded to YouTube every minute (according to the first few sources I found when I searched). That would necessitate 18,000 people watching the videos coming in non-stop 24/7 to maintain vigilance against this using monitoring tactics on YT's side.

Since I don't see YT hiring 18,000 (probably closer to 50,000) people for this purpose, huge changes are needed to avoid all of this. Stricter requirements for uploader eligibility, internet-safety education in schools (most of these videos appear to have been uploaded by the same children as in the videos), stricter requirements for commenter eligibility, etc.

However, given the massive amount of content uploaded to YT, it's hard to imagine a 100% effective solution that doesn't involve an equally massive amount of people sifting through the videos 24/7. Computers are flawed, but the problem has obviously gotten to a point where something has do be done.