Cartoon nursery rhymes directed at as low as even 1 year olds will sometimes have ads popup for a tv show containing drugs and guns. Completely inappropriate!
EVERYTHING that deals with children whether directly or indirectly is strictly regulated, and rightly so.
Television programming as an example, for 70 years only permits certain ads to be displayed on children's shows.
YouTube should be regulated by the FCC in regards to this and very easily can have a checkbox for advertisers and providers to check that says the content is for under 13 or not.