In this video, many of the techniques involve Uke grasping Tori's wrist. Before Uke grasps Tori's wrist, Tori extends his fingers to expand his wrist. After Tori's wrist is grasped, Tori rapidly contracts his wrist by forming a fist causing Uke to become momentarily unbalanced. Uke responds by relaxing his arm and upper body, allowing him to regain his balance using his supporting leg(s). However, whilst Uke's upper body is momentarily relaxed Uke has no option but to follow Tori's wrist allowing Tori to manipulate Uke to apply Aiki to unbalance himself. An example is given below.

At a time of 0.46, Tori extends his fingers as Uke comes to grab Tori's wrist. After Uke grabs Tori's wrist, Tori contracts his wrist by forming a fist, inducing Uke to relax his arm/upper body. Tori bends his arm at the elbow inducing Uke to follow Tori's wrist by rising onto his toes. This action has induced Uke to apply Aiki and become unbalanced by reversing the muscle torque about his front foot joint so as to lift his heel as he pulls back. Aiki-Lead