I'm guessing it still depends on STUN and TURN servers?
Since it's only STUN, and not TURN, the actual transferred data does not go transit through it though.
There's no TURN server specified, and I'm not 100% sure whether the one that's specified there (Google's) does both (so if STUN didn't work, would it fail or attempt TURN?).
Since it's only STUN, and not TURN, the actual transferred data does not go transit through it though.