While it's cool to see this technique applied to consumer video, the general idea has been used in international espionage for a while now. In fact, Léon Theremin (yes, of the musical instrument) invented an early device capable of eavesdropping based on window vibrations: http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#Espionage . I also recall that this is why all of the windows in the White House are fitted with tiny devices that vibrate the windows randomly as a countermeasure.