I watched a clip of an AFF exit and decided the instructor had got it wrong. He had not. What I was missing was the one piece of information that decides the whole question.
In the clip the instructor leaves before the student. My reaction was that this is backwards: the instructor should not be gone before the student is out of the door. Going by the student's exit, I assumed she was somewhere from AFF category C2 onwards, and at that stage the ordering I had in my head would have been right.
I asked people on the ground who knew the progression better than I did. The student was at a later category, where the student is supposed to follow the instructor out. The order in the clip was correct.
That is where I should have stopped and asked rather than concluded. A clip shows you a body position and an exit order. It does not show you the category, the brief, or what the student and instructor had agreed before boarding, and all three decide whether what you are looking at is an error.
I have not linked the video or named anyone in it. Working out who was in a clip and then publishing a judgement about their jump is the part I got wrong, not just the conclusion.