Every greenfoot project that is changed to a fullscreen project can be opened with greenfoot. In this case you can download the scenario, start it and click on the screen to start a fullscreen game (a very simple one).

Oh shit that was the wrong scenario. Sorry I thought this was my Full Screen Demo scenario. (they look very similar). To your question: You can open the scenario with greenfoot. If you start it offline there will be a new frame coming up where you can enter the path of your scenario you want to change. Then you just click on the rewrite directory button and your scenario will be rewritten into a fullscreen scenario. You just have to make your world a subclass of FullScreenWorld and change the constructor. But I'll change this in the next version of this scenario so you don't need to do anything yourselves.