Most recent scheme to stop oil

I heard on the news BP is in the process of inserting a 6 inch pipe into the 21 inch riser to suction the oil out. Supposedly there will also be some type of contraption to stopper the end of the riser with the suction pipe inside.
They also said that the top hat is on the ocean floor near the site but was not going to be used at this time.

Hope this idea works. I see several issues with it.
1. drill pipe is also in riser,so it will be hard to stopper the end of the riser.
2.back pressure will build and increase flow in the area of the riser that is crimped.