From what I read on eurosport, it's a matter of keeping some blow on the diffusers. Since not all cylinders cut off they are still blowing on the diffusers, producing downforce in the matters (I think it's that, not 100% sure). It's suppose to be forbidden also. And in that article they were claiming that it was Mercedes who counterattack the accusation about their F-duct with this cylinders thingy on Lotus - Redbull Renault. But yeah not really clear lol.
For the Qualification, nice jobs from the Mclaren guys and from Schumacher. If it rains, maybe we'll see the Red Baron back again ^^ Kinda disapointed with Redbull performance, let's see what they can do in the race tho.