(submitted by Keith Lofstrom - Eugene may change this)
Eugene Kovalenko builds a small dynamic structure with a pulley, a rubber loop, and a rotary hand tool:
Watch the video carefully - you can see some interesting physical effects. Most particularly, how tiny changes in "launch angle" can cause large variations in tangential motion - there is no way that Eugene could make the loop "land" accurately on a second pulley, without some kind of extremely rapid midcourse correction.
Also, Eugene's loop is connected and made of elastic material. This also feeds oscillations. Most particularly, as the material loses velocity at the top of the arc, it must "compress" because the mass flow rate stays the same. The only way this solidly connected loop can compress is by splaying out to the side.