firefox3: where are hidden the plugins settings?

[Pierre Frenkiel]

hi,
I want to view a conference which is broadcast via rtsp.
If a make a realplay call, that works perfectly, but I'm unable
to convince firefox to use realplayer:
On 1 machine, it opens a totem plugin, on another one, it opens the
mplayer plugin, and none of them works.
What drives me crazy is that it's totally independant of any user's 
configuration: I get the same thing if I remove the .mozilla directory!
It doesn't come either from mozplugger: same results if I remove 
/etc/mozpluggerc.
I  also checked that it doesn't come from mailcap/mime.types.

So,  where are hidden these damned plugins settings?

-- 
Pierre Frenkiel