Thanks for the pointers.

I am using Cabnola on N810 with the standard media player - not mplayer.
Yes, in fulloscreen mode tapping on screen - click-drag, nothing seems to work to minimise the screen back to windowed state.

I actually wanted to get the volumen control in Canola itself, leaving the system volume control at high. But if the screen does not minimise, then there is no way i can get at the Canola volume control.

But thanks for the fullscreen button on the top, why didnt I think of that.