I'm trying to use the preview in Jubler. In the external plugin wizard, when I browse to the directory where mplayer is and click on it, the program doesn't do anything. It just freezes. If I let the program automatically search for mplayer then it never finds it.
I installed Jubler and have used it with MPlayer OSX Extended on my iMac i5 when it was at 10.6.4. Off the top of my head I'll suggest you verify mplayer can even open that video without using Jubler. You should also probably mention if you have Perian installed. I probably followed a walkthru at videohelp.com to setup my subtitling apps.