Comment 28 for bug 90261

I may have found a work around. I am running Xubuntu 7.1 and using the Mplayer plugin in Mozilla. As you described there is no volume control, no link , ikon , or information link. While clicking around in the applications menu I started XMMS and discovered that although there is no input showing in the display the volume control built into its GUI actually works. I guess this means that XMMS has set itself as the default player but that Mozilla doesn't look there before starting the Mplayer plugin. I hope this helps.