Firefox with mplayer-plugin won't play

[Ean Kingston]

I can't seam to get mplayerplug-in to work with firefox. The plugin appears to 
load fine. The video box shows up in the browser, the media appears to 
download (buffering) and then the thing stops (stopped displayed). When I 
tell it to play it just goes back to stopped.

Oddly, if I use mplayer at the command line with the url (copy from the plugin 
menu pasted to the command line) everything is fine.

Does anyone have an idea what I might have missed:

here are the ports, all installed from source.
mplayer-gtk-0.99.7_11
mplayerplug-in-3.21
firefox-1.5.0.1,1
linux-flashplugin-6.0r79_3
linuxpluginwrapper-20051113

and a broken acroread7