Ohh, that's cool. I checked the link you posted first, and, correct me if I'm wrong, you can not only make an object that can be walked under, but create whole maps without using tilesets?
I can't check the video at the moment, for I am not home, but I will definitely do later on.
Question, though, how big can said parallax maps be? Let's say I wish to create a town using this method, are there any limitations I should keep in mind?