application/x-mplayer2

PROBLEM: I went to a site to listen to streaming music and it showed a broken-looking-icon saying I need to install some plug-in so I clicked on it and it said missing application/x-mplayer2.

SOLUTION:
open a terminal, run as root:

yum install mplayer mplayer-gui mplayerplug-in
answer yes to install when asked.

then to find .so files are I used
find / -name *mplay *.so

I then got outputs that looked like below
/usr/lib/mozilla/plugins/mplayerplug-in-qt.so
/usr/lib/mozilla/plugins/mplayerplug-in-rm.so
/usr/lib/mozilla/plugins/mplayerplug-in-dvx.so
/usr/lib/mozilla/plugins/mplayerplug-in-wmp.so
/usr/lib/mozilla/plugins/mplayerplug-in.so

I then when to the plugins folder under where I installed firefox (to find out where you install firefox)
I noticed that there are other .so files under this folder too so
from above list of .so files, I just manually made links to those .so files by running
ln -s /usr/lib/mozilla/plugins/mplayerplug-in-qt.so mplayerplug-in-qt.so
ln -s /usr/lib/mozilla/plugins/mplayerplug-in-rm.so mplayerplug-in-rm.so
ln -s /usr/lib/mozilla/plugins/mplayerplug-in-dvx.so mplayerplug-in-dvx.so
ln -s /usr/lib/mozilla/plugins/mplayerplug-in-wmp.so mplayerplug-in-wmp.so
ln -s /usr/lib/mozilla/plugins/mplayerplug-in.so mplayerplug-in.so

I am guessing from the above qt is for QuickTime, rm is for Real Media/Movie, dvx for DivX, wmp for Windows Media Player and the last one is for general plug-in but then it's a guess, moving on.

I just closed my browser and re-opened firefox and went to my streaming music site and it worked.