"But the researchers came up with a second technique, using the "rolling shutter" typical on digital video cameras, to extract enough information from the video to still recreate high-frequency audio."
Find article here: http://www.theguardian.com/technology/2014/aug/05/mit-crisp-packet-eavesdrop-audio-sound
Paper: http://people.csail.mit.edu/mrub/papers/VisualMic_SIGGRAPH2014.pdf
Magic Lantern - DSLR cinematography extension and spy kit. :)
No doubt ;)