Silverlight is a multi-browser, multi-plugin that allows media companies to deliver video more cost effectively on a variety of different browsers
Silverlight uses Windows Media Video technology and Society of Motion Picture and Television Engineers’ VC-1 video standard to allow transmission of interactive video on full-screen high-definition and mobile platforms.
Silverlight is designed to complement other Microsoft improvements to its .Net framework, including enhanced media encoder, accelerated video publishing and improved scalability.