How to prevent a Webplayer Game from being saved locally?

Is it possible to hard code a Web player game so that it will load a particular scene if it is -not- played on a specific website?

My concern is that I am about to post a game to the Steam green light program and would like to provide interested users with access to my game as it currently stands, but would prefer that the game not somehow be downloaded and saved locally... so when I pull it from my website later on, there are no copies floating around out there.

I tried to set up a WWW to check if a text file existed on a specific website path, along with a crossdomain.xml file, and I still got the security errors relating to not having the correct cross-domain-policy file in place. I verified the path, the crossdomain.xml is in the exact same folder as the textfile I'm trying to verify. In case it is relevant, my site is being hosted by GoDaddy.

Joseph.