I just spent few hours trying to make Flash Player to stream FLV files (Flash videos). Everything worked on testing server but not on the other one. As you may guess, the other server was Microsoft IIS, and SWF files were playing ok, but not FLV. Problem is that Microsoft IIS 6.0 requires a MIME type to recognize that FLV files are streamed media. And all you have to do to fix that is to add new MIME Type:

Associated Extension: .FLV
MIME Type:flv-application/octet-stream

And that’s it. Everything is working now.