http://members.aol.com/jnaudin509/images/mgmnu.htm
As I understand it, you insert a cylindrical magnet (probe) into a circular
array of magnets (gate). The repulsive forces of the like-poles push the
probe out of the gate. The exiting force is 2.5 times greater than the
entering force.
I haven't built the described device (money's tight right now), so I could
be wrong about this...
When inserting the probe into the gate, don't you experience some kind of
resistance? I'd think the probe would be 'pushed' out when inserting, and
then pushed the other direction after it got past some kind of 'threshold'.
What I'm getting at is that the extra force you have to apply to get the
probe past this 'threshold' may actually be the over-unity observed.
Perhaps the gate works like a 'magnetic spring'.
Think of pushing a marble through a small hole in stretchy material (a fat
rubber-band). It's hard to push through at first, but when enough force is
applied, the marble shoots through the hole, exiting with a high velocity.
As I said before, I haven't built this device. I'm just speculating based
on my experience when toying with refrigerator magnets. Try keeping the
probe magnet stationary, and bring the gate to it. If it's actually
'pulled' through the gate (and accelerated by the gate from 0 velocity),
then that would be something.
I bet it would simply be pushed from the gate.
-pb
PS: The link to the video of the device in action is dead.