Those video's are relevant in that that is the exact method I'm using just with a d8b. Yes some of the connections are different and I've had to adapt to what I have on hand, but essentially the same.
I'm using a TRS out of the AUX sends and the BUS outs are TRS as well(db25->TRS).
The signal probe IS TS. Nothing plugs into the signal probe. I realize that that might be where the confusion is coming in as far as the diagram goes. The diagram is shit, lets forget the diagram.
Nothing plugs into the Signal probe. The signal probe plugs into either an amp or back into a channel on the board so you can hear the tone that is being sent out the AUX and BUS outs. Now in order to hear the tone from those outputs you connect the alligator clips(ground) to the sleeve(ground) of the cable coming from the AUX/BUS and you touch either the Hot(tip) or the cold(ring), of the same cable, to check to see if there is signal present on both pins. In a truly balanced signal you WILL hear the tone coming from both the tip and the ring.
I've done it using a different interface, I'm not crazy.
-Casey-i'm going grey-Pittman