The application of Aiki in the techniques demonstrated by Gozo Shioda is analysed below.

At a time of 0.12 Uke grabs Tori's jacket. Tori places his arm on Uke's forearm and induces Uke to apply Aiki by rapidly transferring his weight to Uke's forearm, by lowering his body. This causes Uke to momentarily relax his upper body and to extend his front leg in preparation to resist the downward force. The muscle torque about Uke's foot joint of his front foot is then in the opposite direction to that required to resist being pulled forward. Consequently, Uke becomes unbalanced to the front. Aiki-Lead

Other techniques in this video which use the same method of applying Aiki by suddenly pushing or pulling Uke downwards to induce Uke to reverse a muscle torque about a joint can be found at the following times:-

At 0.18 and 0.34 Tori suddenly pushes downwards on the Ukes arms to induce the Ukes to reverse the torque about their foot joints to push upwards, causing them to become unbalanced to the front as they pull Tori.

At 0.56 Tori suddenly pulls downwards on Uke's left arm/jacket to induce Uke to reverse the torque about his waist joint to pull upwards, causing Uke to become unbalanced to the front as he pushes forwards. This technique is repeated at 2.12 by Tori pulling downwards on Uke's right arm/jacket. 

Note, during this technique Tori remains stable due to the direction of Uke's pushing force, which is directed along Uke's arms, passing through Tori's waist joint. Therefore there is no torque about Tori's waist to unbalance him to the rear.

At 1.14 and 1.17  Tori suddenly pushes downwards on Uke's arm to induce Uke to reverse the torque about the foot joint of his front foot so as to push upwards.  Consequently, Uke is then unbalanced as he is pulled forwards by Tori turning away from him.