...but bottom right isn't "back to previous screen" for anything other than the media-manager and the full-screen player. Plus, those are the only two screens that don't have a "link to the main menu". Therefore, it seems logical to place the "back to previous screen" in the same spot as the "link to main menu" for those two screens.
Honestly I'd rather keep the normal top bar always visible even in those two screens. I realize that would not work for full-screen video as you could not make it disappear after 5 seconds, but can you bring back the top bar in the media manager?. I'd be happy with the "X" button where it is if you shortened the whole thing to make room for the top bar. On second thought, if you kept the top bar I would place the "X" button at the same co-ordinates as the "Media-Manager" button in the Now Playing list.
...anyway, just my opinion
Question: Is it possible to change the function of clicking the top title-bar? (do something other than go to Media-Manager)
EDIT: I guess "Exit" is in the bottom right of Settings too. Can you add the top-bar in settings? I really think it would be best with a truly ALWAYS-up top-bar. The existing "Main Menu" button in the upper left could instead be a "back" button which would always take you to the main-menu anyway within 1, 2, or worse-case 3 clicks in the exact same area.