... right now I'm stuck!
Indeed and we cannot help you. Unless I'm completely out to luch what I see is:
(1) the videos are only offered on your self-hosted wordpress.org site;
(2) you are charging your readers if that wordpress.org site to become members in order to view the videos.
Hence it seems that "complexity" of some viewers being able to view videos and others not being able to view them may be a contributing factor to your problem, or not.
The bottom line is that this wordpress.com forum is only for posting questions and answers about free hosted wordpress.com blogs, and the blog you appear to be having the problem with is a wordpress.org software install for self hosting.