I added a rule (flash file), specified the new flash file I want fiddler to respond with (use instead of the browser one). I've cleared my browser cache, and every time I play the stream, the browser flash file is captured again (instead of auto-responding) with the one saved already!!!
It used to work just fine, but now it appears as if the auto-responder (although checked) is not working at all...it's just a pass-through!!!