QuickTime Pro: About the “Conform aperture to” setting http://tinyurl.com/39xqu5c
QuickTime Player Pro 7 introduced a new conform setting – basically an overscan for video played back on computers, something I’d prefer it didn’t do.
Fortunately it can be changed with the QuickTime 7 player (not the QuickTime X player) as the instructions in the linked Knowledge Base article show.