"Get up, up, up!" from the 2nd demo. There's no single level file because it hasn't been changed since the demo release.
Also note that another backroute-removing change has been made to Eye of the Lemming. However, a redownload isn't really nessecary, the change just reduces the number of blockers from 5 to 1.
So for the 2nd demo, the changes since the original release of it:
Backdraft: Builder removed. It is no longer possible to bomb through the wall, it is no longer possible to dig and bash under it. (Downloading new version on the previous page is reccomended.) The difficulty rank is also changed, it is now Danger rather than Wimpy.
Eye of the Lemming: 10 lemmings instead of 2 (still requires 100%). 1 blocker instead of 5.
All other levels are the same as before.