catching a file when it arrives in the browser

Im working on a video player at the moment (a flash one). Before the video starts, the player receives a manifest.f4m file. I would like to detect WHEN this file is requested and WH开发者_开发知识库EN it actually arrives (ie the time for the server to generate it). I really have NO idea how to do it, but it should be possible using javascript because Firebug and even Google Chrome's console timeline are able to detect this "event".

Do you have any clue ?

Since it's in Flash, Firebug may not pick it up in the Net tab since those calls don't go through the browser's API. You may consider using Fiddler. It will show you just about everything.