With a MCE remote if I press the back button while watching a video the only way I can figure out to return to fullscreen is to press the live tv button twice. Is there a button that goes to fullscreen that I've overlooked?
If you have the Euro MCE remote, then the red button at the very bottom is the fullscreen toggle.
If you don't have the four coloured buttons down the bottom, then you have a US version and there is no fast way to do it, I think.