QTXAutoPlayFullscreen is a SIMBL Plugin that alters Quicktime Player X to automatically start playing when entering full screen.
It also automatically resigns full screen when the movie has finished playing.
In order to enable SIMBL plugins you need to install SIMBL, you can download the latest release at: http://www.culater.net/software/SIMBL/SIMBL.php
After installing SIMBL you need to download the QTXAutoPlayFullscreen.bundle.zip file, extract it and drop QTXAutoPlayFullscreen.bundle in ~/Library/Application Support/SIMBL/Plugins/
You can create the folder if it doesn’t already exist.
Now the plugin will be loaded when you start Quicktime Player X. If it was already running you need to restart Quicktime Player X.
You can configure the plugin by changing the defaults in the com.apple.QuickTimePlayerX preference.
This is easily managed by running one of these commands in the Terminal.
defaults write com.apple.QuickTimePlayerX QTXAutoPlayFullscreenEnabled -bool YES
defaults write com.apple.QuickTimePlayerX QTXAutoPlayFullscreenEnabled -bool NO
defaults write com.apple.QuickTimePlayerX QTXAutoResignFullscreenEnabled -bool YES
defaults write com.apple.QuickTimePlayerX QTXAutoResignFullscreenEnabled -bool NO