From Monkeybread Software:
New QuickTime users are sometimes confused that they need to buy a copy of the QuickTime Pro Movie Player to get full screen movie playback. This application provides this for free :-) Just drop a movie on the application icon or use the Open command from the menu. Press the "esc" key at any time to quit the player or use QuickTime's movie controller to navigate through the movie. As source code is included, feel free to modify this application to your needs. If you like the application, feel free to donate some money on the website as the downloads costs a lot of webtraffic.