Quicktime Player X: Enable auto-play feature

It’s possible to enable the auto-play feature for video files in Quicktime Player X. Use the following Terminal command:

defaults write com.apple.QuickTimePlayerX MGPlayMovieOnOpen 1

To make the command take effect, you need to restart QuickTime.

Change value 1 in 0 to revert to the default setting.

defaults write com.apple.QuickTimePlayerX MGPlayMovieOnOpen 0

Screencast: