I'm not super exposed to popular YouTube stuff, but was visiting family recently, and lots of kids watch it. What was interesting to me is how a lot of it appears to just be inexpensive gameshow-style stuff with lots of product placement. I guess this hits the sweet spot between cost and revenue. Also surprised how much discussion of money/pricing their is, e.g. "we're going to eat this thing that cost 50,000 dollars" seems very popular.