While the title is about lightbulbs this looks like the same principle as using a laser to measure the vibrations on the surface of a window in order to listen to the audio inside a room (something that's been science fact since at least the early 90s). I don't see why the laser or optical sensor couldn't be measuring vibrations of something inside the room: a clear line of sight and a mylar balloon might be the perfect tool for such passive surveillance trick.