That's a really good video, Steve; thanks for posting it.
He says the generator puts out 18 Volts, so the rectified pulses from one of the phases is passed through the MOT's primary, to feed the cell. (May as well use a battery charger for testing) . The part I don't get is how a 10 times step-up transformer can fire a spark plug with 18 V. on the primary? Perhaps a really close spark gap. And there's no hv diode, BUT the MOT's secondary circuit is a closed loop. Firing the spark plug may affect the transformer's operation momentarily, but no hv is going to the cell.
The wire coming straight down to the top of the cell allows the wire's magnetic field to pull the bubbles inwards as they rise. This likely causes the cell to output at least some amount of the less energetic Orthohydrogen. That's good for bonding with turpentine vapor, but alternate wiring approach angles might be advisable.
