Worked fine for the one file that I downloaded so far. There are minor cosmetic improvements that I would like to suggest:

1) it should be possible to undo an "Automatically select quality" setting (i.e. completely remove it without toggling to a different setting)

2) The icons used on the download screen are not that self explanatory and they should provide some tool-tip text

3) the plugin's tool-menu (see plugin's icon in Firefox's toolbar) seems to list duplicate video entries that should better be filtered out (no big deal since download buttons are also directly available in the video's widget)