The issue isn't with one platform being more open or closed than the other; if you kids want, they can watch pretty much anything they want. They have YouTube and a browser, how are you going to stop them? I sympathize with your distaste for crude advertising, but every platform has it's fair share of people abusing it. Just a few months ago, developers were coming out en masse to denounce Apple's weak regulation in the app store, filtering obscenities but completely missing predatory pricing structures, ponzi schemes, stolen code and frequent double standards/unequal ruling.

The bottom line is that the internet is scary, and your kids are growing up faster than any generation before. The more you try to interfere with stuff like this, the more animosity they'll perceive in your relationship.