If you have multiple displays connected to your Mac and you have tried to use Front Row, you have discovered that Front Row only wants to play on your primary display (the one with the menu bar). If you want Front Row to play on the big screen TV connected to your iMac, or through a projector connected to your Macbook, you need to change your display preferences to move the menu bar to the secondary display, and then move it back to your normal configuration when done. Not very convenient, is it?
Front Row on the Big Screen fixes all that. Simply run it, and choose which display Front Row should use. Now Front Row will use that display, without moving your menu bar. So when you are done with Front Row, you can continue using your Mac as if nothing ever happened.