I saw this on Reuters and had to laugh. In theory I suppose it makes sense. People walk all day on a treadmill instead of sitting in a chair. Miraculously, they lose weight!
I actually have a setup just like this at home. I secured a large Elfa shelf to the handles of our treadmill and set my laptop up on it. There's plenty of room and it works very well. However, working, even at a slow walk, is not exactly a sustainable activity. An hour is about all I can handle before the bouncing and movement begin to wear on my eyes and posture.
So, interesting concept. Not practical.