From the description, I'm having trouble
picturing how that device would work.

Does it "cut out ice cubes" from the block
of ice that it sits upon? If so, where is
the hot water held? Sorry if I'm not
seeing the obvious.

In the second photo, notice the plugged hole on the left, that's where the
hot water goes. If you look in the first picture you'll notice that the
bottom of the cube tray is just past the holes on the side, so there is an
inch or two of room below the tray to hold the water.

http://pzphotosan80.blogspot.com/

Rob