Children always depends learning on what they see. They have little known of recognition on how they will interpret it as whether it's a good thing or a bad thing. If children saw something funny and people often try to just laugh it off, they will saw it as a good thing, even though it has a visible thing of hurting someone. You can't control on what they see on youtube. Of course, it all depends on the parent or responsible adult to control and limit on what they saw. There are still good and learning videos on youtube that children must see. Have them limit watching youtube and as much as possible refrain on teaching them on how to navigate on youtube. Always make sure that the autoplay is off so that videos would point to other topic.