There a startup named CrowdProcess doing something similar. Their business plan is to pay websites to include their javascript, and sell the computation time to developers. This way, the websites can cover hosting costs without resorting to ads.

From the fine article he reversed the phase on one and added it and listened to what fell out

Would seem you could do a lot simpler version of this digitally, decode both into raw / wav files, then calculate the diff between the two raw files

Isn't that exactly the same?