When using the VGA Cable on a 1280x1024 screen.
The entire Single Player displays properly as 720p letterbox widescreen while
the entire Multiplayer mode displays incorrectly as 'full-screen'.
Cross posted on Xbox.com, and IGN.com
Proof:
The camera wasn't moved whatsoever and no changes were made to any settings anywhere.
SinglePlayerSingle Player
MultiplayerMultiplayer