You can do what you're trying to do with WebRTC - but you want to enforce a relay, so the data flows through the server and you can write the frames to disk. What that'll do is essentially eliminate the P2P part, but still make all the data flow over UDP rather than TCP, keeping performance high and bandwidth low. It's about the best you can hope for without going with something like flash media server.
For support in IE, you'll need a plugin of some sort - it doesn't support native WebRTC, and there's no support for native UDP connections in Flash either, so it's either Java applets or custom plugins.
We've done the heavy lifting for basically what you're trying to do with IceLink (I work @ Frozen Mountain). Oh, and to enforce the relay, you have to suppress any peer-candidate pairs that don't come through the relay (since WebRTC can have multiple candidates from multiple sources, just suppressing the options you don't want will ensure that the relay is the only option left).
Hope that helps!