In my keyboard there are F5-F12 which have multi-media function when click them with Fn key together.
I tried the volume control in windows, it works just fine. I wonder how does the keyboard wire the signal to the OS?
By the way, there are Fn key for play/pause/prev/next and it even work with my foobar2000 mp3 player software. I am thinking it is not software level trick.