You've seen this in crime dramas: hard bitten detective employs computer genius with attitude to conjure vital clues from grainy and low-resolution surveillance video by using some unspecified form of "enhancement." Scoff all you like, but MIT computer geniuses can now enhance video enough to track your heart beating.
The technique that MIT's Computer Science and Artificial Intelligence Lab (CSAIL) has developed for video enhancement is called "Eulerian Video Magnification." You may (or may not) remember Euler from high school, but what's going on here is that the researchers are separating out each individual pixel from a video and then looking for subtle changes in color over time. These changes can either be actual color changes of subjects in the video, or they can be indicative of cyclical motion.
Two scenarios that illustrate this technique are both straight out of the movies: by enhancing color changes in the skin of a person, it becomes possible to measure their pulse by watching blood pump around under their skin. And if that's not good enough, it's also possible to enhance motion such that you can see an infant breathing, or even how much your arteries bulge when blood moves through them. Watch this in action in the video below; make sure not to miss the crazy motion enhancement starting at 3:18.