Hi, I have just made an account to post this warning. I am definitely not the right demographic for Mumsnet - I am a 20 year old guy, but I feel like you might really want to hear about this!
There is a huge amount of Minecraft videos aimed at children called which is extremely disturbing. They are often called "Minecraft Monster School" or something similar. They feature (male) pregnancy, blood, torture, horror, and some are even pornographic. And this is all going on on YouTube and is aimed at kids! I would not be surprised if many of the people making this stuff were paedophiles. There is a huge amount being uploaded, I counted at least 50 uploaded just today and many of these videos have millions of views.
Even the ones which don't feature the more obviously inappropriate stuff are still weird, psychotic, and probably harmful. They basically consist of 10 minutes of completely incomprehensible nonsense: the same funny sounds repeated over and over again. For a young child, I imagine it's really highly stimulating, addictive, and no doubt will be harming their sleep, attention span, learning, and probably also screwing with their development in other ways. Add in the really inappropriate themes and I genuinely think this could have a lobotomising effect on a toddler or even an older kid and we will only know the true psychological damage once they become older.
So just be really vigilant about this sort of thing. Check their history. And please, just don't leave them on YouTube unattended, it's a really dangerous place for kids (used to always be for teenagers only). I wouldn't even trust YouTube Kids because not everything is checked properly and even if it is, it's still going to be worse for them than Cbeebies.