They can't. It uses a bunch of technologies they licensed, but which they have no rights to open up for others to implement. Apparently when he made the announcement Steve Jobs thought that it was all based on open technology, but the licensing turned out to be a can of worms.
That sounds really presumptuous, since chances are high @amelius knows about the alternatives, and since it's still a great point even with the alternatives; if I want to use Linux, great, good for me, but I'm not going to walk around trying to convince all my friends & family that are happily using FaceTime to switch to something that requires an installation, is harder to use, and is not integrated with the calling features of their devices.
No, they use a bunch of nonstandard extensions to WebRTC that basically amounts to the plugin. This is why the plugin is required on Firefox, even though it supports WebRTC.
I am curious about this, since I assumed that Google would have put in quite a bit of effort to make sure that Hangouts is competitive in terms of bandwidth usage across platforms.
Do you have any performance figures?
And a harder question: any ideas as to why this is the case?
