]It is very unusual to ban photos and videos from seminars. Without these all we can go by are the words that Dan and others have written. If we weren't supposed to debate their ideas why did they post them in a discussion forum? I have tried very hard to follow the arguments they are making. I'm good at doing that, by the way, I teach people how to do this at the highest levels. My initial posts asking for clarification were met with indignation and demands that I read all the old posts. I did. They are confusing and hard to read. I said so. I was asked to post specific question (it wasn't my idea) and I did so. The questions were not answered. They were reasonable questions. Then the insults started.
I can't speak for this being true in the aikido world, but in many other martial arts they may be out right banned, need prior permisson, or may be considered poor form. I've been to a number of seminars in japanese sword arts where they were discouraged (by the Japanese guest instructors), and other arts where they were banned. They were banned for two seminars I hosted as well.
Seminars run by americans had a lot more liberal take on the presence of cameras.