We've rolled out a small yet important patch which disables the demos feature under normal conditions, and tells the user not to use the feature if they did manage to open it up.
The reason for that is two fold:
a) The feature is not yet complete, and is missing some important fixes
b) Playing a demo you got from someone else is a security risk we did not initially anticipate
Demos will remain unavailable under normal conditions until these points are resolved.
In the meantime, have some eye candy to speculate over what's to come in the next content update:
Changed files in this update