Prevent Hotlinking

Preventing hotlinking of .swf files and streaming is quite tricky. Not an easy task. There are always ways to go around this.
You can generate a token and send this to the server when client connects. Server could validate the token and decide if connection is valid.

The new FMS 3 server should have some extra protection, but I haven't discovered this yet.

Flash Media Server does not show to the end user exactly where the MP3 file is. Being that it is streaming the file with the FMS service it won't be actually "serving" the file to the client, so they won't know where it is exactly coming from. That's in relation to a web server which will give the path to the file because the browser has to go retrieve it.

i don't know if this is made easier by Media Server, and i am not a coding expert, but this is a tricky task you are trying to accomplish i think.. of course the end-user can always view the 'Activity' log in his or her browser and get the URI of the source file if it is being offered as a progressive download. one possible solution (and again i don't really know the answer) is to embed the MP3s into your SWF files and then set restrictive permissions using Flash Professional CS3 disallowing re-importation of the SWFs... check out the devnet center for security and media topics. of course embedding the audio into the SWF is not the ideal solution... some serious coding and you could use a couple of encryption libraries or Amazon S3's signed-URL feature to time-limit (and individually sign) the access to the MP3 file(s). This would provide a unique URI for access to the MP3 file upon each request for it, that is signed and can expire in as little as 10 seconds.. that way the file cannot really be downloaded as the access URI will expire as soon as the streaming has begun.

complicated topic here that i know little about but i thought i would try and help =)

JD