To me it sounds like he is doing a variant of the Uli.
From his description it sounds like all he is doing is keeping a tight tourniquet grip at the base (with just one of his hands) with his index finger right on the CS-chamber (the chamber on the underside of the penis). After a while he lets go with the index finger, kegels in some more blood, trap it again with his index finger and “milk” the new blood forward by moving his index finger forward.
If I understand this correct, he is using a over hand OK-grip (thumb and index finger closest to the belly.).
Edit: After reviewing his drawing I think he is using the standard OK-grip (pinkie finger closest to the belly). Using the over hand OK-grip should work as well since it would allow for a tourniquet grip that is much closer to the base. Also, the CS-chamber is much more flexible then the CC-chambers so one probably do not need much force or a great range of motion to “milk” in and trap more blood to create a higher pressure in the CS and the glans with the index finger.