In the beginning, center on the SanChin line, and later at the end of the video, is my old friend and MeiBuKan instructor, Masaaki Ikemiyagi. The viewer shoukd note the explosiveness of his movements.
I remember once back in 1981 at Naha University, where he was at one time, Captain of the KaraTE team, and later Coach, he was dissatisfied with a students SeiSan, during a college demonstration that we were watching. He told the student to get dressed and bring him his "the student's" gi. Ikemiyagi Sensei put on the gi, and after the next part of the demo was finished, went out onto the floor and performed SeiSan. I swear, when he landed his heel on the floor after the front kick at the end of SeiSan, with a loud CRACK, he actually damaged the floor. No lie! He walked funny for about a week afterward also... But man!