Just to be clear, it doesn't matter if you use Firefox and your chat buddies use Chrome or Opera. As long as everyone is using a browser that supports webRTC there shouldn't be any compatibility problems.
That's about all there is to webRTC. In my experience, the call quality isn't quite as good as you'll experience on Hangouts or Skype, but it'll get there eventually. In the meantime, happy chatting.
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