Monklord, have you tried the test program to see whether the media control plugin is actually hooking into ffdshow? Initially for me it wasn't. I tried reinstalling ffdshow a couple of times and I tried reinstalling the plugin a couple of times. Each time, the test program wouldn't show that I was controllin the media player.
Finally, I went ahead and deleted the ffdshow folder and deleted the plugin. Then I reinstalled ffdshow and then reinistalled the plugin. After that, it started working. Again, sort of. I can do most everything except FF and REW.