silverlight 的视频用普通的下载器无法下载，在同事的推荐下，用了orbitdownloader，果然灰常强大~~~

Orbit Downloader is a free Silverlight videos downloader which can help you to download videos from Silverlight freee and easily with great speed.  Also Orbit Downloader can download and manage FLV videos from almost all of social media websites like Youtube, Myspace, Dailymotion, Metacafe, Google Video, iFilm, Yahoo, Pandora, Radioblogclub, IMEEM, iJigg, Silverlight..

http://www.orbitdownloader.com/silverlight-downloader/download-videos-from-silverlight-free.htm