QuickTime X is really cool and one of the many great improvements in Snow Leopard, but I was really surprised to find out that QuickTime X no longer automatically plays movie files on open, you’d think since I just opened the file I’d want to watch the movie! Thankfully resolving this is just a matter of entering a command in the Terminal.

While digging around to figure this out I also uncovered some more QuickTime X hacks, like forcing QuickTime to stay full-screen even when it’s in the background, or how to force the titlebar to always show or always hide.

Each one of these commands can be reversed by changing the value from 1 to 0 or vice versa

Autoplay QuickTime Movies on Open:

defaults write com.apple.QuickTimePlayerX MGPlayMovieOnOpen 1

Automatically show subtitles and closed captioning:

defaults write com.apple.QuickTimePlayerX MGEnableCCAndSubtitlesOnOpen 1

Never show titlebar:

defaults write com.apple.QuickTimePlayerX MGCinematicWindowDebugForceNoTitlebar 1

Always show title bar & controller:

defaults write com.apple.QuickTimePlayerX MGUIVisibilityNeverAutohide 1

Disable rounded corners in QuickTime X Player:

defaults write com.apple.QuickTimePlayerX MGCinematicWindowDebugForceNoRoundedCorners 1

Keep playing movies full screen even when you leave QuickTime as inactive window:

defaults write com.apple.QuickTimePlayerX MGFullScreenExitOnAppSwitch 0