Thanks for further replies.
My main worry is not the one video posted from my child's party onto the YT account. My child isn't in it, the party wasn't at our house, no identifiable info/location etc. However two other children are in it. The kid has posted it up with emoji faces on the kids involved but not massively effective. I suppose I could take the angle of - this needs to come down, kids were put in my care whilst at party and now a video of them is up on sm with no consent - but at least one of the two has a similar YT account and has commented on said video!
I think I will have a word generally to say, I've found this account off the back of the party (having seen something being uploaded and thought I'd double check etc, can put this on my other half etc as being the one who'd "seen the account name" etc), and as she said no uploading was happening that I thought she would want to know as a) it has happened at our kids party and b) thought she would want to know given her child has an adult YT account that is open to all to view and with hundred of subscribers that she seems to be actively trying to increase.
In an ideal world I would hope that she takes this seriously, gets her kid off SM, which is good for her kid, my kid and the others in their peer group. But I suspect she either already knows and doesn't care/won't see the risks in it.
I fear some consequence may come to my child if she handles this in the wrong way, ie. her kid says your Mum moaned about my YT etc. But I feel on balance I need to say something so will have to run the risk and deal with anything else as it arises.
I will consider reporting to YT depending on how the conversation goes, but if parents are on board then another account would probably just be created.
The issue of the school is interesting. As others have said it's a parenting issue first and foremost and can understand school taking view of "if it's not on school time/property, not our issue." the school is very good and does a lot for safety for the kids and also for parents, but the parents actually have to engage with the info don't they!
But OTOH, is there a safeguarding issue here? ie these 8yolds have open adult YT accounts. In my mind that puts them at risk. Would the school not want to know about that? I don't know. School won't be my first point of call however.
Having reflected on this, my initial worry about coming over as judgmental has lessened. As I am judgmental and this is not on! I won't be telling the parent what to do but I also think I shouldn't apologise/feel awkward and just set the facts out as they are.
Still remain depressed that I am having to deal with this all as a parent of an 8yo. But it seems like it is probably just a small taste of things to come :(