LIGHTFAKTOR is a Cologne artists collective 
experimenting with the "possibilities yielded by bulb (long-term) exposure and painting."
The technique employed has been coined "light writing" - Wikipedia's definition:
"Light writing is an emerging form of stop motion animation wherein still images captured using the technique known as light painting or light drawing are put in sequence thereby creating the optical illusion of movement for the viewer."
The resulting images/video are pretty amazing! See below. By the way, interested in trying-it-yourself? The friendly collective has even posted some How-To advice on their Behance page:
These are the basics:
To get the best results you need a tripod. The exposure should be around 10-30 seconds or longer if needed. Stay in front of the camera and do your writing. To not overexpose, set the camera to about ISO 100, and close your aperture as much as possible. If there is still too much light, you might have to use a ND-filter. It is always nice to integrate the surrounding into your picture.
We use flashlights, biking-lights and flashing LED lights. They all work with batteries, so that we are mobile, you also get nice results with fireworks & torches.
There are 3 different type of lights we use:
Xenon: makes a warm golden light.
LED: makes a thin precise line.
Cold Cathode: thick line/fat cap.
But the best results you get by experimenting, use filters and things which reflect light…
Now you'll need some post production help. Here's exactly how to do it from Creative Cow: How to write with light in After Effects.
LIGHTFAKTOR's work:
