[marquis]

Flash can be blocked, or not installed. If you are running a modern Chrome or Firefox, there is no way to stop this from running. (edit: apparently you can now block WebRTC entirely in Firefox, but Chrome has to be recompiled)

[tracker1]

I wish chrome had an advanced configuration interface similar to firefox's for this kind of thing... I'm actually surprised WebRTC doesn't at least prompt for access, similar to location, camera and similar requests.