I just watched the video. The only identifiable OS was on a PC running a copy of Windows from the NT 3.5 or Windows 3.1 era.
And running XP would not save money in all probability. The loss of productivity would more than equal the cost of licensing.
The only way any of them are running XP is if there is a specific software they need that was never updated for Vista or Win 7. Or as a testing bed.
In my opinion, of course.
I'm not trying to defend the fact that they might, I'm just stating why they may think it's a good idea.
As stated, I'd love to see the game have full support for DX10 and DX11.
I just have a gut feeling that this isn't the case, but I really hope this feeling is wrong.