With things like this, getting exposure isn't a matter of having the money to host your content, but simply a matter of being popular. The more popular you are, the more likely that you can offload static file hosting to those consuming your content.
My girlfriend brought up a good point: is there any way to opt-out of seeding?
Or maybe DOS your site, by pretending to be a PeerCDN participant but instead sending large chunks rate limited to 0.5Kb/s. The SHA1 hash check will stop them being used, but only after a long delay. People could be having a bad experience and you wouldn't even know by watching server stats.
How is the connection between peers encrypted?
I hope webrtc does better with NAT.
http://i.downloadsquad.switched.com/2011/03/23/sendoid-offer...
For a P2P scenario it makes sense to have something like a chatroom.
Edit: Incase anyone is interested, I have a chat log up: http://ancarda.net/rtccopy.log.txt
I blogged about it back in 2009 anyhow (under the self-effacing title of "Opera is about to change the world?!"!).
Your example translates the file into a base64 string to send over the unreliable channel, which ends up being a pretty big performance hit compared to a native binary transport.
All of this is to say: WebRTC is getting there, but it's still going to be several months before it's ready for more than demos like this.
Firefox does have indexeddb, but if you want to do seek operations you're out of luck.
EDIT: To explain more, without seek writing dealing with large files is incredibly expensive, you have to write everything you've got to indexeddb every time you want to modify it.
Warning:
-Data is transmitted here without encryption, directly to the other users in this WebRTC room. Use caution if sending sensitive files and communicate file passwords through a more secure channel."Your browser will likely crash if you attempt to send a single file larger than 100MB, your mileage will vary."