I didn't notice this, but as you said it is a long demonstration.
I only saw Mitsuteru sensei in the hombu instructor demos and as uke for his father. He only appears in the programme
in section 19 under "Hombu Shidoin" on page 8 (Page 4 of the PDF
). Are you saying you saw him make another unofficial appearance in the Defence Agency Rengokai embu? The video has already appeared on Youtube
but the quality isn't sufficient for me to make him out.
Hiroshima is quite a long way from Tokyo and I do not attend the All-Japan Aikido Demonstration very often. When I saw Mitsuteru Ueshiba at the demonstration, he was a high school student and his father was still alive.