Sorry, is this like Liam Neeson - drop a handgrenade in one part of town then another and Liam (or rather is listening to Snowden microphones) can work out where he is?
I believe he is implying the NSA or other entity using the microphone input from cellphones (or maybe the microphones placed around many major cities on utility poles?) to do the locating. I think it would probably be theoretically possible, but I don't recall anything in the leaks about them ever researching that sort of capability.
They can just listen to the 50hz ground hum in the signal coming from his audio equipment and determine which relay stations are providing that power ..
It's never exactly 50 Hz, as the frequency is affected by load and generators can't compensate this perfectly. So record it in many locations, then correlate the signal extracted from audio/video against the database.
Can that possibly work IRL?