As I was wandering through the morning tabs, I happened across this [Link]

and I immediately had the thought that this would not work. For me at least. It might work when I am only looking at the screen, but when I am keying or doing anything else that requires cognitive processing I suspect I should lose the walking thing and end up tumbling. Which would not be good. 
This raises the question of whether other people do things at desk that do not demand them to think, or are they able to actually do two things – well – at ones? I fear I cynically suspect the former more than the latter.