WebRTC with PeerJS: iceConnectionState Disconnecte

Question

I have a node app in each of my machines running this example on localhost with a PeerServer key that I made. When I try initiating a call between the two, the connection is established (as in, the receiver says it got a call from the sender). However, the Media Streams are also initiated (black boxes show up in the video divs), and then the connection stops because "iceConnectionState is disconnected".

What could be causing this problem? Is it some sort of configuration issue? I'm using two Macs running Yosemite.