After watching his video 4 more times, I think you are correct. It does appear that he re-routed the feed motor wires to the secondary of the second transformer.
Since he apparently spliced into the trigger relay on the motherboard and connected that lead to one of the primary leads on the second transformer, it looks like he spliced into the the blue fan wire (its blue in my HF) on hot side of the switch and connected that to the other lead on the primary side of the second transformer. So assuming the trigger relay is the AC neutral and the fan wire splice is the AC hot side, then that all makes sense now.
Have I got it right?