nuno filipe barradas I'd note that system sound generally does require a sound capture driver and/or a way to hijack system sound and/or a way to virtual cable sound from a program (video file player for example).
nuno filipe barradas Developers looking this request note that it currently can't be done on Mac as there's no API to implement. It's theoretically possible on Windows but might only be through certain browsers like Chrome.
Basically, WebRTC doesn't support pulling in system sound.
The workaround would be do use a virtual cables variant from the file player with the audio which Rendezvous may see as a device input.