As Google owns both YouTube and AdSense, they maintain monopoly over YouTube's Ad network.
I personally don't think that getting payed in other currencies then BTC is a problem.
However you still have 2 solutions:1. Exchange USD(payed by YouTube) to BTC
2. Earn BTC through affiliate marketing. - How?
Many services pay you % for promoting their products or getting leads/consumers on their service. All you need is an affiliate link, and a niche YouTube channel. When you've got both, start promoting the afflink in the Video description and why not in the Video itself.
I'm an YouTuber for 2 years, trying to make my best in creating video tutorials. When i reached 5000 subscribers many services started contacting me to be their Affiliate and to promote their products. (This is my YouTube channel:
https://www.youtube.com/user/EhaiosCOM)
Avoid Over-Saturation!Well. Watching a TV channel which shows Ads every 5 minutes is not very interesting (at least for me), so be very careful at when you promote the product (in the video) and how much time you talk about it. Otherwise your subscribers may migrate to your YouTube competitors.
Have other questions? Or need more explanations?