When browsing http://www.w3.org/TR/media-frags/ the bottom bar is shifted towards the right and hence the arrow up button is not available. Further, it seems that zooming moves the arrow out of screen. 
When browsing http://www.w3.org/TR/media-frags/ the bottom bar is shifted towards the right and hence the arrow up button is not available.
Further, it seems that zooming moves the arrow out of screen.