As BrotherBob said, there is no particular privacy safety with the use of any operating system, whether it's Internet Explorer, Chrome, or any .. the video and audio feed in the Hangouts, or any Web routed service for that matter, is passing
thru the server infrastructure of the service you are using .. IOW, Google hosts Hangouts, the video and audio pass
thru Google by default .. so no matter what your software is, you can be recorded or listened in on .. not to say you are, but how would you know .. ??
Unplugging your webcam/microphone is the only way to really insure that while you are not "Hanging Out" your system is not able to be remotely accessed and monitored .. I know all this sounds like some sort of dystopian Big Brother scenario, and it is in a way .. but "free" is never really "free" .. Google
thrives off information .. it's not the warm and fuzzy World it likes you to think it is .. and neither are any of the other major browsers or search engines ..