Personally, I kinda liked it. Not that it's the most graceful thing in the world :lol: but it's a respectable attempt to address a very important social need.
Children pick up on things, obviously. Even here where it's on the news every day and causing a lot of anxiety. I can't even imagine (and I don't want to!) the kind of upheaval the kids in Japan are going through with this even apart from the quake and tsunami. Their lives are being turned upside-down and they're entitled to some explanation. There's simply no way to make something this complex and technical accessible to a child when it's hard for most adults to grasp.
But anyone can get the concept of bodily functions. If it re-frames the issue in a way that children can (sorta) understand and makes it less intimidating then who cares what adults think about it? It would be interesting to talk with children there and ask them if it was helpful. I hope it is. There's more than enough fear over there already.