Lots of good idea right here! dTube is a good DApp, but as you said, there's a lot of room for further improvements. Letting people tip easily sound like a great and easy way to let the content creators earn some extra money, and it's probably not difficult to implement for the developers. Ads also sound like a smart thing, and I'm for it as long as it's up to the content creator to chose if they want it or not.