What I mean by domain locking is keeping someone from downloading my game and host the file on a different domain (url). If it isn't a built in feature, are there scripts available?
If you don’t want to hardcode URLs into domain checking scripts (see simple one line solution above), here’s a simple C# script I’ve made for Unity that lets you check the domain that the webplayer is running on, against a list of domains.
https://gist.github.com/andyman/e58dea85cce23cccecff
It will redirect to a specified location if the domain is not found. Just drag the script onto a GameObject in your first scene, and set the domains and redirect URL in the properties in the Inspector tab. Feel free to use/share.
I uploaded the web player version of my game to only one site, and within a few days, it was hosted by more than a dozen sites without my permission.
Lesson learned: Put a domain locking script in your game from the onset. Here is my article about the lesson learned.
You can do this, just look at the following url: http://unity3d.com/support/documentation/Manual/Unity%20Web%20Player%20and%20browser%20communication.html
Its the most bottom code fragment witch does what you need:
Application.ExternalEval("if(document.location.host != 'YOURDOMAIN.COM') { document.location='WHERE_TO_REDIRECT_YOUR_USER; }");
You can put this code wherever you wish. But i would put it when the first scene is loaded.