[MPlayer-DOCS] how to make mplayer let realplayer play some files?

[quixote]

I'm new to mplayer, and love it, on the whole.  My one problem is that 
there's an .ra file that it tries to play, but can't for some reason.

Rather than try to work with mplayer to fix it (unless that's easy to 
explain in a step-by-step way), I'd like to be able to just use 
realplayer to play those files, which worked fine and doesn't require 
any extra effort from me.  But I can't find how to tell mplayer to leave 
.ra files alone. 

There's only one site in question: 
http://www.cartalk.com/Radio/Show/online.html and I'm trying to listen 
to the concatenated link of all ten segments of the show. The mimetype 
shows up in mplayer as audio/x-pn-realaudio Object.  I use Firefox 1.5, 
run Fedora 3.

Mplayer launches when I click on the link, but does nothing.  The 
actions associated with files (under Edit-Prefs-Downloads-View and edit 
actions) won't let me point to a specific different plugin or program 
for that filetype.  I can only choose "default plugin' or 'save to 
disk'.  I tried editing pluginreg.dat manually, but I may have done it 
wrong because nothing happened.  "about:plugins" tells me mplayer is 
enabled to open pretty much everything, which (I think) is okay except 
in that one instance.

I've looked in the mozillazine forums, helixplayer / realplayer, the 
mplayer docs, and nowhere can I find anything about how to make 
different plugins work together.  It's all about how to use the given 
plugin in isolation.

Am I trying to do something impossible?  I should say that I get lost 
pretty quickly unless I have the exact commands I need to enter, so, if 
you can help, remember that you're dealing with a n00b!

Thanks!