Teaching a dog to use the bathroom toilet.

I have seen cats that have learned to use the bathroom toilet to do their chores; but i had never seen a dog do that, and it would never have occurred to me to even try and each a dog to do that.
Amazingly, there are many dogs that have actually learned to do this !
I don't know how hard it was to teach the dog to do this; but these dogs actually use the toilet, and then flush it, and some even have learned to put the lid down afterwards.
(if even a DOG can do this, why is it so hard for MEN to learn ?)

http://youtu.be/0TqlFp1bvck