Guys, I went to check what you have reported.
Here is what I did.
1.I made sure that the user I am testing with is not a Moderator. Let's call this user "James". So James is not a moderator on my site and he registered when 'Free' user role was set to be default one.
When, as an admin, I go and try to change his role I see following page:
James, is assigned a "Free" user role and can post videos at this stage. If at this stage I assign him "Underflagged" user role, he will have 2 user roles. Defalt+ new one. Oxwall works so that + to - gives +: so if one user role doesn't allow something, and another one allows, system will allow the action. So if I don't want James to be able to post videos I have to remove "Free" role from the list of his roles.
2. As a site admin I go to admin panel>user roles>and make another role a default one:
3. Then I go back to "James" profile and try to change his role again. I now can remove "Free" role from the list of Jame's userroles. I assign him "Underflagged" user role which doesn't allow posting new videos.
4. Now James can not post videos on my site.
If now, as an admin I will go and check another user I will see following page:
Now the system has removed "unremovable" default user role and I don't have to go through the step #2 again and again. You need to change the default user role only once in admin panel. Now I can go back and make "Free" role a default one again and in future it will no longer be "unremovable".