Yes of course;) that to say almost… you don’t have to be administrator member, but you can never see or get posts from a closed groups.
PS. I’ve also modified the sample entries so now they link to a real FB entities (group and app which I manage) so the samples will display feed from this group where ever you include the [fb_group_feed] short-code.
It seem it sometime takes the WordPress trunk some time to update or rather the plugin SVN (I had to reload the plugin page 8 times before it showed up).
It has the v1.1 available for download now, that’s for sure :o)
Thank you AmRes for pointing out this error.
This has now been fixed!
Please upgrade your plugin to the latest version (v1.1) for this to take action and to get few new options.