ORTC API is now available in Microsoft Edge (opens in new tab)

ORTC can interop with WebRTC, so you could create a an Edge to Chrome or Edge to Firefox scenario. In fact, you can implement (to some degree) the WebRTC APIs in terms of the ORTC APIs.

ORTC is a W3C standard feature (http://ortc.org/) currently requesting for implementations.

For this specific demo we wanted to demo ORTC to ORTC communication so you need 2 browsers that support it. At this moment only Microsoft Edge on the latest insider flight does.

There are several initiatives to make the bridge between ORTC and WebRTC: simplewebrtc.com/audio.html is one that does that for audio.

Edge (the particular topic of the blog post) currently only runs on Windows 10. I'm sure that was the assumption made by the article author. Presumably, if you had the right Chrome build I presume you could also attempt to use that. (Although the last I heard Chrome was still supporting an older draft of the standard, and maybe that was also included in the assumption here?)