>If the af-on button is release, then it will always fire as >in the video. > >However, if I keep the button pressed it will only fire once >the green dot has been shown (in af-s) or is showing (in >af-c). Except in the circumstances I described above. > >I interpret it as follows: as long as I keep the af-on >pressed, I tell the camera "keep trying to acquire focus >and fire only when this is achieved". Once I release the >af-on button, I am telling the camera that I don't require >autofocus anymore.
That is definitely one interpretation, but this is not how it has worked in the past, and it makes trap auto focus impossible. Hence, the OPs complaint (among many others). I believe Nikon will probably remedy this to work as it did in the D700 in the next firmware update.