I "think" I can see some possibilities for how that could "maybe" work without gravity. Maybe three or more.
One way involves this effect.
http://www.youtube.com/watch?v=RBN_cYEgeMAAnd the other involves a rubber band or similar to be used.
Can't be sure, but I'll try to explain how I think some ways would work.
1. The most likely in my opinion is a large slowly rotating magnet under the bench (rotated by hand or some other way).
2. The rim of the wheel looks to be aluminium to me, the effect of the steel (I doubt it is pure iron)
ball moving back and forth and the changing flux field of the magnet along
with the eddy current effect in the aluminium and the very slight movement of the magnet
could cause a motoring effect.
3. If there was a small rubber band (or similar) inside the hub connected so as to have tension
placed on it beforehand by winding it backwards, but not strong enough to start rotation
with the weight of the ball on it, then when the ball is moved the weight of the ball temporarily
relieved enough for the rubber band to start rotation and maintain it for a while.
4. Possibly a combination of the two or some other way.

Many possibilities.
I'm not saying any of those things is how it is done, just that that is what I would look for
if I was able to see and check it out.
I don't see how it could possibly do any good to think about it too much unless it is for real
and does actually work like that. Going by some of the other models they have, I think they are all powered.
It's not a perpetual motion machine though because it is a man made machine, it will stop.
Only a natural perpetual motion machine is possible, by definition I think.
Cheers