How is screen sharing implemented in google hangouts?

Question

Google

I started to study webrtc and actually made a multi-user video chat, now the question is how to implement its recording.
the first thing that came to my mind was to write a stream from each user and then glue it (but this won’t get the full picture, since the slicing will be complicated), the second idea that came up was to record directly from the browser window.
I only found it in the open spaces: https://www.webrtc-experiment.com/RecordRTC/ , but there they ask to install a plugin, but how is it implemented in hangouts? he seems to be quietly fumbling without plugins

Answer 1

The best way to record a video chat is to have a server side MCU that mixes the video streams into one picture. The rest are crutches.
Screen sharing can be done with a quick installation of extensions (inline).
In this case, the user does not need to go to the store and download something, and he installs the extension by clicking on the link in the browser.
Extensions will come to be made and uploaded to the store for both Chrome and FF.
Without them, no recording will work due to the browser's security policies.

Answer 2

And when I first used it, hangouts asked me to put an .exe file, so it's unlikely that it works without a plugin

Answer 3

I have ubuntu 14.04 LTS and chromium, it doesn't ask me to install any packages. In general, I'm trying to figure it out