All rights reserved?
It's good to know that TeacherTube is adding an open license option. The site was down when I was checked, but by all means, let me know when/if they do.
Creating groups of websites according to licenses is a little tricky. Some of the repositories, such as WikiTeach, outline freedoms that are similar to a particular Creative Commons license, but do not explicitly use it. WeTheTeachers has the following in their terms of service:
"You also hereby grant each user of the WeTheTeachers Website a non-exclusive license to access your User Content through the Website, and to use, reproduce, distribute, prepare derivative works of, display, download your User Content as permitted through the functionality of the Website and under these Terms of Service."
Not exactly a recognized open license, but the freedoms granted have some similarities. Yet it doesn't seem appropriate to put it with CC-BY-SA sites. So I've marked them All Rights Reserved, for lack of a better heading (at least when I wrote it).
Websites like YouTube are only open in the sense that there is no cost to view. You bring up a good point about wanting to remove them. I would like to think some more about what constitutes the bare minimum of open before removing listings.