I had an astronomy book as a kid that showed how to make them by pointing a tripod-mounted film camera at the pole star and leaving the shutter open for several hours.
(, Mon 26 Nov 2012, 14:40, Reply)
I've done it myself. The difference being that I've never seen them done as a video, with the trail being smeared out like that.
(, Mon 26 Nov 2012, 14:45, Reply)