In roles, you can give a role the power to mute a webcam : once muted the webcam was closed on all users. However, the user could play the webcam again.
We have added a new parameter in config called muteWebcamPreventsPlayingCamAgain that prevent other users to play his webcam again : his webcam button will be removed from the user list.
The option to enable the public webcam mode only in certain rooms and per roles would be a great new feature too