For thousands of years parents did intend to benefit from their childrens' labor - this notion together with high child mortality rates was impetus for agricultural families to have lots of kids. They could be put to work in the fields.
While I agree with this statement in 2017, and I find the Youtube channel in question a bit freaky (no pun intended), your statement made me think about the exploitation of child labor throughout human history. I think those of us in the developed world today are happy to live in a society that doesn't exploit child labor. However, in today's free market, the internet, and social media particularly, sometimes creates incentive systems that may reward exploitation directory (ToyFreaks; putting your kids to work on the farm) or indirectly (Facebook might find that they have the power to influence the incidence of depression in their users, and that depressed users bring in greater ad revenue; YouTube might find that videos which educate children bring in less ad revenue than videos which appeal to base desires and offer little enrichment).
I don't have kids so maybe my opinion isn't as relevant but if a child wants to do something (be an actor, youtuber, or participate in some competition) it doesn't necessarily seem like exploitation to me even if the parents somehow benefit.
The potential for abuse is there... But how do you classify and regulate something like that?
There is simply too much room for emotional manipulation as the parent pushes the boundaries on what they're making the kids do -- or even, at its most benign, simply pushing the kids to keep being in front of the camera, long after the kid wishes the channel would stop.
Parents should not be earning money off their kids. The balance of power simply isn't right for that to work in many cases.
I'm sure there are exceptions, but time and again we get examples from YouTube showing why this can be terrible for the kids.