Streaming should be free, as should the protocol it's developed on top of, so anybody can use it, and trust it.

Revenue streams come from supporting the back-end telcos (billing, active traffic mgmt & shaping), and content generators (disney/pixar etc), and a couple of other things I'm not ready to talk about just yet ;-).

Well, if you had a website that cataloged and displayed the streams, much like Twitch.tv, then people can still find streams and subscribe to them in much the same way they do over at Twitch, while the site gets a cut.

Additionally, broadcasters can still do Paypal donation links, like they do over at Twitch.

Advertisements playing before videos, I'm not sure how it could be done, but it probably could be an overlay before the stream starts, or just a HTML5 video that loads first and must finish before the P2P stream begins.

In this case, this is like asking how you would monetize TCP. This specification is a transport protocol and could apply to multiple use cases, not including video.