"I want to keep my URLs secret, so I sit with my back the wall. Why would I want to broadcast my favorite xxx URLs to everyone in the room? Ok, some rooms, yes, but in the living room....nope."
Umm, your watching porn while in a room full of people? Classy 8-) But seriously, I don't see the point of this either; the fact of the matter is, I don't think Google sees a point either, it's an experiment.
I did have to ask, though, why would using this plugin involve "temporarily" storing URLs on Google's servers? Is a multi-ghz PC now not fast enough to do basic signal processing? Are they sending off the sent and received URLs (and/or sent and rececived sound when a URL is detected) to be able to analyze possible failure modes?