I managed to move somewhat freely around the Elemental demo. The biggest problem is that the no clip "ghost" mode doesn't move vertically for some reason, so getting the right height to move around is a pain.
Anyway, here's what I did (type all commands without the quotation marks):
1. To speed up the demo and not wait too long for the free camera, open the console (~ key) and type "slomo 100".
2. Once the demo ends and you're in the free camera mode, type "slomo 1". (note: If you want to slow down time, type in decimals, for example "slomo 0.1" etc.)
3. Type "walk". This will put the camera in a player walking mode and you'll instantly start to fall through the world.
4. Type "teleport". This teleports the camera to a predefined point in space, somewhere at the center of the castle, but pretty much inside the floor. However, since you're in walk mode, you will fall onto the mountains below the castle. You can now freely move around.
5. Here's the tricky part. The only way I managed to actually change my vertical position is to walk around the mountains and squiggle my way to a higher position without falling off the map. You can't jump so it makes the task a bit harder, but it's doable.
6. Once you are at a desirable height, open the console and type "ghost". Now you'll be able to walk around and through walls, so if you're at a reasonable height, you can take some nice screenshots.
If someone has an idea on how to make the camera move vertically, please share. Also, if you want the camera to move faster, you can speed up the game with "slowmo 100" which speeds up camera movement as well.
Here are some screenshots taken with FRAPS:
