Can you explain what the bug is?
I understand that some people are able to view the demo, so what's wrong with me and diogoschneider?

Yes I do.
As I said in my original post, it behaves the same.

Yes, it does say: Your session has expired. Please login again.

Adding ?debug=1 to the URL (http://demo4.zimbra.com/zimbra/mail) opened a window with "Branch: main".

Refreshing the window,...

After clicking the "Skip Registration, Go to Demo" button, I see the captcha image, and after I type the characters and submit, I wait a while, and then I always get a login window in which I don't...