Ffmpeg

The plugin is not available yet but here's how you can get it now:

1. download VCD & MPEG Tools (Make sure you get the one "for Mac OS X")
2. mount the disk image (it should mount automatically, if not, double click the .dmg file)
3. context click it (that is a right click or control-click) and "Show Package Contents", looks like this:
   
4. go into "/Contents/Resources/"
5. find the file "ffmpeg", see it?
6. HOLDING THE OPTION KEY drag and drop that file into /Library/Application Support/kJams/

Now you're all set. Soon i'll just make an installer.