If the texture and displacement are drawn to match, AND if the UV mapping is proper,
this method will work neatly.   For most belts, the only thing you really see is a moving
texture anyway.  (Imagine the fan belt on a car, where you see the label zooming past
repeatedly.)

The exception is when the belt has compartments or buckets like a
grain elevator "leg", in which case you'll need real physical motion.

The UVmapping is really the hard part.  I found it best to model the belt as a nice
round cylinder, then map it as cylinder, then morph it into the long belt shape.

Or you could try Draw-A-Cord, now that it works for you... :)

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