Firefox is currently ahead on the data channel, right? They support sending blobs / arrayBuffers directly, while Chrome doesn't yet have a reliable transport or binary data support.

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.

It's true that it supports binary / reliable transport already but there are some very annoying not-to-spec issues. As a library developer, if I added code to support it, it would just go to waste because in BugZilla they've already patched but not pushed changes to these issues.