Re: Video of Seichiro Endo Shihan
I believe Endo Sensei used to be quite forceful or hard when younger until he injured his shoulder. He started looking for ways to accomplish the same things while using less force. In the interview I read, he would ask people to attack him strongly and would try to figure out how to move using no strength. If the kuzushi (balance break) is there, the technique should be effective regardless of the strength used. To me that is the aiki element. Relaxed power.