To record Miscrosoft Silverlight you can use screen video capture software.

To record http:// .flv stream undetected, you can use webstream dumper of Replay Media Catcher.

You can also

• capture RTMP and HTTP streams undetected using Bit Recorder,
• capture Windows Media streams undetected using WM Recorder in the PRO mode or WebVideoCap,
• capture Real video streams undetected using WM Recorder in the PRO mode