How It Works...
Unless you believe in paranormals,
you'd guess that it has something to do with the bridge (pointed by
finger)
You would be right!
It's a LEGO electric plate connecting the two motors.
As you spin one motor, it acts as a generator causing the opposite motor
to spin also.
Here's the underside of the electric plate.
This plate is available as
part of some LEGO sets.
You can also purchase a 9
piece accessory kit (#5037)
from LEGO SHOP AT HOME 1-800-453-4652 for $6.75
Other neat motor ideas