using mplayer instead of flash plugin for Iceweasel

[Rob Owens <rowens@ptd.net>]

I've replaced the Iceweasel flash plugin on some of my systems with mplayer
by using the Greasemonkey extension with the following script:

http://userscripts.org/scripts/show/24999

It works nicely, uses less CPU, and sound works on my LTSP thin clients (a
big plus).  

Can anybody suggest how to make this a default for all users?  I'm not sure
how to handle it since the extension and the script get installed in the
user's $HOME directory by default.

-Rob