The adapter is just a through connection, with pin 1 on the first connector wired to pin 1 on the second connector, pin 2 to pin 2, and so on, for all six connections. I used a spare circuit board from an inline dynamic timing boost module I designed many years ago because it already had holes and traces for the two connectors. Then I added some 0.025" square post connectors on perfboard to bring out all three sensor signals and a pair of grounds.

Chuck mentioned in the video that he always plugs the ESC and the motor into the ends of the adapter marked "ESC" and "MOT", but the adapter really doesn't have a "direction", so the cables could be swapped and still function properly.

As Roelof has shown, there are other ways to gain access to the necessary signals. I'll show another example below. It is simply a spare sensor cable with the ground and Sensor B wires cut, stripped, twisted, and soldered back together, with the wires formed into small loops for the scope probes to grab onto. Ground is pin 1, which is on the left side of the connector if the wires are facing up and the metal crimp connectors are visible. The Sensor B signal is on the third wire from the left:




It's a good idea to space the loops apart from each other with a plastic or wood insulator so they don't short out.