Forget watching water balloons pop or bullets tearing through fruit. The next generation of super-fast camera is 15 and a bit million times faster than a commercial slow-mo camera like a Phantom Flex, and can show the movement of light itself.
A research group at Lund University in Sweden has demonstrated a camera with the ability to film at some five trillion images per second.
That's not five trillion discrete frames per second, mind you. In order to split time down that finely, the camera pulls several images out of a single frame. While the "shutter" is open, several different laser light flashes hit the subject. Each laser flash is visually coded, so it can be separated from the rest of the information in the frame afterwards using a decryption key.
In this way, it's quite similar to the previous 'world's fastest camera' record holder out of the University of Tokyo, which managed a paltry 4.4 trillion frames per second.
As for what such a thing might be useful for? Most likely scientific and industrial research, where it's quick enough to visually track processes that occur on a picosecond or femtosecond scale. The research team that invented the process spends most of its time working on combustion, which is reasonably well understood at the macro level, but is driven by a number of ultra-fast processes at the molecular level.
The team will use the camera to document the chemistry of plasma discharges, the initiations of different chemical reactions, and the lifetime of quantum states, both in combustion situations and in biological tissue.
Lord knows how big a camera card you'd need ... If you recorded the blink of an eye (which takes around 0.3 seconds) and then played it back at a nice cinematic 24 frames per second, it would take a little under two thousand years to watch.