I don't recall any comments about a giant ball. It's hard to tell in that oddly shady video with the widely placed angle but it looks like his thighs might be horizontal (i.e.: flat). People use notebooks on their lap at very angles and it's work well because the display supports itself and you can adjust the angle to what is ideal. How is that possible with the Surface? Where are those videos proving a 15* angle will work just as well?
I honestly have no answer to that except to say that you should get a case. Then again, the Surface might not be for everyone. Personally I'm at home a lot and I mostly use my laptop on the table, so "lapability" isn't a problem for me. If I manage to find enough money for one I'd use it as more of a consumption device, or on-the-go work, because lack of a CD drive is a big issue for me.
But everyone is entitled to their own opinion, and I'm not going to try to push any opinions in your face. My SN says it all