I think it's an alternate recording button that act as a start/stop button that allows you to record for an arbitrary amount of time, rather than recording the last 30 seconds.
Or maybe, if I dare say so myself, it's a button to toggle a "free camera" mode in games
I C what you mean. I'll say that I like my ABCs neatly packed under my XYZs.Well this isn't a Genesis controller. So i don't "C" what purpose it has...
(I'll C myself out now)