The system used is called STEAM, which means Serial Time Encoded Amplified Microscopy. This system is used to amplify the light per pixel. At the speed of the camera, light cannot travel fast enough, in turn, there is not enough light to magnify. STEAM system was used to compensate for this issue.
STEAM works by illuminating the subject using infrared lasers that cycle through various wavelengths of infrared light at a breakneck rate. The sensors pic up the wavelengths amplifying the original signal that would normally be very dim.
At the moment STEAM can only produce just 3,000 pixels per pic, in comparison to conventional camera that can do millions of pixels per pic. There is talk going around about a new project led by Keisuke Goda's team. The plan is to procure a device that can take multi-megapixel pic's at one trillionth of a second producing around 100 million pic's per second, now that is fast!
The good news is that one of the biggest investments in our modern world, apart from natural resources and food goods, is making consumer electronics faster and smaller than they already are. This means that in the not so distant future we might be using enthusiast grade technology similar to STEAM but by then it might be the norm. For example, imagine STEAM systems integrated onto the backside of your iPhone 20Gsi.
Water drops using a conventional fast shutter camera
Lightning using a conventional fast shutter camera
Concept iPhone with possible nano light sensor for camera