A stream of very viscous syrup falls from a nozzle onto a moving belt. Initially, the belt is moving so fast that the thread is just pulled out straight. As the speed of the belt is reduced, the thread first bifurcates to a meandering state, and then to a "figure eight" state. Finally, the thread falls into a coiling motion similar to what it would do on a non-moving surface.
The movie is in real time. Its large, 26MB.
Go here for the low resolution YouTube version.
See Meandering instability abstract for a publication about this effect.