The video segment is excellent.
I would place the exhaust end of your call between the thumb and forefinger of your right hand,closing the remaining fingers down as if to form a tube, thus extending the insert of the call. Make sure nothing is obstructing the exhaust and slowly blow a steady stream of air through the call,relaxed air as if you would gently blow out a candle,no voice,no grunt just air. Now don't change anything once the call is underway with this steady stream of air,now take your left hand and make a slight C-shape and SLOWLY bring it around the end of the tube you have formed with your right hand. You will DO THIS WHILE BLOWING A STEADY STREAM OF AIR. While slowly bringing the left hand around,you should feel the call change sounds as well as hear it. This is the break point. If you are able to do this ,repeat it,then rep this until you can automatically find this point through hand positioning with your even eyes closed. This is the hand position for you,may not be the same as mine or the next guy,but it is the point where you are able to make that reed close and slap down on the toneboard of your call. Do this before ever trying to make a two note,three note,cluck,whatever. You can never advance to making note shapes UNTIL you can find this break point. You will have to go stupidly slow,because if a burst of air is used,it occurs too fast to zero in on the proper hand position.