I think it should be done on a warning system, doing it by pm is just going a bit too far towards a 'nanny state' for my liking, and I think we should all be adult enough to have the choice of whether to read something or not - I dont read as much as i would like, as not all the links show up in my e-mail notification, and I have to be careful how much I read at work, but I dont want that taken away from me, but I also dont want tons of pms.
In regards to YouTube vids, I think there shoudl be some guidelines, I dont mind watching the genuine ones that could help people, but very few of the ones I have seen posted on here have been like that, the rest have all been more what the owner found funny.