Versteckte Quicktime X-Einstellungen: Autoplay, u.a.

QuickTime X Hidden Prefs (Disable the Rounded Corners and more)
To set any of these, go to terminal and enter in the code for whichever preference you want to set. Remember, to reset the setting to its default value, just change the "1" at the end to a "0" (or vice versa).

Autoplay movies on open:
defaults write com.apple.QuickTimePlayerX MGPlayMovieOnOpen 1

Disable rounded corners:
defaults write com.apple.QuickTimePlayerX MGCinematicWindowDebugForceNoRoundedCorners 1

Never show titlebar/controller:
defaults write com.apple.QuickTimePlayerX MGUIVisibilityNeverAutoshow 1

Always show titlebar/controller:
defaults write com.apple.QuickTimePlayerX MGUIVisibilityNeverAutohide 1

Never show the titlebar:
defaults write com.apple.QuickTimePlayerX MGCinematicWindowDebugForceNoTitlebar 1

Automatically show subtitles and closed captioning on open
defaults write com.apple.QuickTimePlayerX MGEnableCCAndSubtitlesOnOpen 1

Keep playing full-screen even when you command-tab out of QT
defaults write com.apple.QuickTimePlayerX MGFullScreenExitOnAppSwitch 0

http://forums.macrumors.com/showthread.php?t=775514