The restrictions were put in place to keep unregistered members from accessing license-holders-only portions of the site. That includes viewing screenshots, which can easily be uploaded to sites which offer pirated vBulletin versions and rips of skins.
You'll need to have your license verified before you are able to download file attachments (including images) and/or post in certain sections. Don't look for these restrictions to change.
I believe you can get a vBulletin demo at
http://www.vbulletin.com/admindemo.php --- but I have no idea what that mythtalkers.com redirect is all about.
HTH
Jacquii.