Xinema was created due to the lack of full screen playing functionality in Apple's QuickTime Player. It's designed to be an easy solution to this problem. Instead of purchasing QuickTime Pro, you can get this feature for free with Xinema. Xinema provides a floating controller for pausing, fast-forwarding and adjusting the sound volume.
To play a movie, simply drag it from the Finder, drop it on Xinema, and click the Play button.