Youtube and Google+

You post your YouTube to a specific group of people privately when you have Google+ through circles or individuals.

Just make the video private, and then choose which circle, or type email addresses.

Note: If you want to share it with a community but not exactly privately, you can make it unlisted and post it. Otherwise, if you want to make it private, share it with a circle that has the same membership as the group, and then post it to the community so it will appear on the community page.