SparrowTV is a live video streaming platform that uses WebRTC and a simple tree model.
Each peer sends the stream to two other peers, which in turn sends it to two others.
LIVE DEMO
I built this as a WebRTC demo awhile ago. The tree model would collapse under churn and is not suitable for more than a few dozen peers. However, it does promise lower latency than some existing WebRTC streaming demos that use mesh topologies.