Yes, what they’re doing is cutting away parts of the riser, to make way for cutting it off for the 2nd cap.
It appears BP has just cut into the riser pipe with a robot. Junk and oil is flowing all over the place right now. This means they have given up on the junk shots / top kill and moved on to a very risky plan–apparently they are going to try to attach another BOP to the top. This means that oil will flow at a much higher rate, until they are successful. How they are going to be able to see what they’re doing now that they’ve cut it, or attach the new BOP (scavenged from relief well 2) with all that pressure going out, no one seems to know.
Of course, this might not be what they’re doing-but it looks that way. The other possibility is that they are trying to attach the 2nd cap (LMRP) to the riser, but they wouldn’t have needed to stop drilling relief well 2 for that, or take it’s BOP.
Also, the robot dropped it’s saw.