How to stop Quicktime X playing the previous video

An annoying feature of modern OS X (ever since Lion) is that when playing a video in Quicktime,
the previously played video will also start playing.
Thankfully, this can be disabled by opening terminal and typing in the following command:
 
defaults write com.apple.QuickTimePlayerX NSQuitAlwaysKeepsWindows -bool false
 
This should stop QuickTime from saving the opened windows when you quit it. If you want to
revert the behavior, change the false to true. Map