Okay yeah you can just use the greasemonkey script + MicroB

1.) apt-get install greasemonkey-webaddon (or install from HAM or I suppose fapman or whatever)
2.) Open microb and restart it a couple times
3.) Open greasemonkey
4.) Visit http://userscripts.org/scripts/show/9789 and click the Install button ( http://userscripts.org/scripts/source/9789.user.js )
5.) Answer yes to install the script
6.) Visit http://www.facebook.com/pages/Fire-F...r/145513041952 (or wherever)
7.) Choose Save (not Open because it will open in default media player which cannot open MP4)
8.) Open with [g]mplayer and enjoy.