V8
Was checking this out this afternoon - mad scientist stuff - deriving audio from visuals of a chip packet, mind boggling.
Aside from snooping on people, the only other practical application I could come up with was revisiting footage where the audio was degraded/missing, though you'd still need a reasonable FPS otherwise it might not be much use (I was thinking historical stuff).
AlanRatcliffe
Great stuff!
I remember a few years ago they recovered a sound of a voice from the pre-recording era. An Italian scientist in the 19th century (IIRC) had used a machine to draw a graph using the vibration of his voice. Modern scientists reconstructed the voice from the drawings. Can't find details of it now, but I remember being highly impressed.