In that 5-6 seconds of observation, did the idea of capturing it using that camera in your hands never occur or were you too busy just puzzling out the image? Do you remember your thought process during that time frame?
When you say it just vanished was there really no motion at all prior to disappearing? Was its vanishing instantaneous or a rapid dissolve?
Regarding the camera it all happened so quickly that all I was thinking about was what it was I was looking at. Had it been there a bit longer I probably would have thought about the camera. Although, I don't even recall if I had a tape in it yet as I was mainly setting up the camera angle, adjusting the iris, etc.