Aiki
合氣

The Origin of Aiki

The legends of Kojiki tell that Prince Yamato Takeru used Aiki for the first time. In 397, the Yamato fought against the Kumaso, who lived in southern Japan in the Kagoshima area and were considered invaders. The prince underwent a misogi at a waterfall and accumulated energy with ritual movements. Then he disguised himself as a woman and went to see the leader of the Kumaso. With the help of Aiki, he managed to kill the enemy. The knowledge of Aiki was then passed on in a long tradition to the Takeda family.
Takeda Sokaku explained Aiki as follows: "The secret of aiki is to overpower the opponent mentally at a glance and to win without fighting."
Figure: Excerpt from "Prince Yamato Takeru attacks Torishi Kaya", by Tsukioka Yoshitoshi.

Ueshiba

Ueshiba Morihei
"True Budo is the cultivation of attraction capable of absorbing the opponent's entire being."
In the video you can see how Ueshiba completely dominates the Uke Terry Dobson mentally and physically. Ueshiba called this type of technique "divine". They were allegedly transmitted to him by the Kami of Shinto.

Tohei

For Tohei, the effectiveness of the techniques was based on the coordination of mind and body and on Ki. Like Ueshiba, he exerts an irresistible effect on Uke, but does not let him suffer. The throwing techniques are fluid and rhythmic.
Tohei no longer speaks of Aiki but only of Ki. This puts the emphasis of the training on the strengthening of Nage, who can thus lead the mind of Uke well.

Aiki Jutsu und Aikido

The first part of the video shows Salahuddin Muhammad at an Aikijutsu seminar in Boston in 2016. The attacker must not feel any contact points. Nage is fully coordinated and can thus control the attacker mentally and physically.
In the second part, Martin Glutsch (DAB) explains how these techniques work. With the help of the gaze, he coordinates himself and establishes the connection to Uke. He then lets flow Ki to Uke, completely relaxed, so that Uke has to bend involuntarily and to fall.
In both cases, the situation begins quite statically. A mental and physical connection to Uke is established. With minimal movements, Uke is forced to follow Nage's will.

Grunick

Karl Grunick cultivated this type of technique very profoundly. He doesn't call it Aiki but KI, which is supposed to mean body intelligence (in German "Körper Intelligenz"). The stability exercises are similar to Ki tests. Obviously, Grunick establishes a mental-physical-psychological connection to the attackers. Some of them are very susceptible to this type of interaction.

MMA against Tai Chi

Master Wong (UK) comments on a fight between a Mixed Martial Arts fighter and a Tai Chi master.
The Tai Chi Master has no chance. Obviously, he cannot establish a connection to the attacker and thus his techniques are ineffective. According to Wong, MMA fighters are drilled for attack to roll everything down.

Yoshigasaki

Turin 2016
Yoshigasaki does not cite either Aiki or Ki here. He builds on form as a fundamental concept. First, Nage has to make a form that harmoniously matches the form of Uke (not shown here in the video).
Then Nage changes the form without changing his position in space.
Nage then changes the position of Uke without changing his form. So Uke falls.
The physical-mental connection between Nage and Uke is not discussed here. The form alone creates the contact.
With this concept, Yoshigasaki Sensei wanted to overcome the older concepts of "resist, defend oneself" and "give in, follow the other".