Justindustrial wrote:
I recently upgraded to OSX Lion, and now when I open a video in Quicktime, it changes monitors when it goes fullscreen rather than staying on the monitor I have it playing on.
In Lion, the full-screen implementation moves the application to the primary display (the one with the menu bar). To have QT go to full screen on your secondary display, you need to go into System Preferences -> Displays -> Arrangement and drag your menu bar to the secondary display prior to putting QT into full-screen mode.
An alternative method is to use QT 7, which doesn't know anything about Lion's native full-screen mode. QT 7 will go full screen on whichever monitor you choose.