Mozilla and mplayer

I made the mistake of removing the check box to "always ask before openin=
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when clicking on a ASX audio link. Now, when I click on said link, Mozil=
la=20
asks me where I want to save a file. How do I get it back to letting me =
open=20
the stream with the app I specify?

Better yet, is there a way to specify mplayer as a helper application? A=
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pointers?

Alan