I can't believe that it has anything at all to do with your FTP setup. That pinball game is just a Java applet. As long as you have the correct version of Java, the game should work fine. I went to the site and played a quick game. The only thing that I noticed is that pressing the "Space" key did not start the game. To start the game I had to use "Control-Space". Then it all worked fine.
That does not work for me. what does happen is, if i put the pointer at the score bar, press space and left-click at the same time, it will start but then quit after a few seconds.
To use the FTP, I did have to excercize the get Java option, It seems that my pre-existing Java was out of date. Perhaps I did something wrong or something went wrong