This free Silverlight extension uses Silverlight 1.0
You must add the Silverlight.js file to the same folder as your webpage(s) running this player.
You can get the free Silverlight.js file off of the www.Silverlight.net website by downloading the Silverlight 1.0 SDK.

Silverlight is cross-browser / cross-platform compliant.

You MUST remove the <!DOCTYPE> tag in your html in order for this to work in FireFox.
This is a known bug with Silverlight and FireFox.