There is a white brush sitting on top of the rail for the control rod driving mechanism...
(From TEPCO's video taken on 8/2/2013):
TEPCO has been trying to get better information inside the Reactor 2's Containment Vessel for some time, and have failed for one reason or another. This latest attempt was to reach inside the pedestal. The attempt failed again, when it simply took too long for the workers to manipulate the camera past the obstacles.
Workers threaded the CCD camera, dosimeter, and thermocouple through the penetration X53 in order to find out whether the CRD exchange rail has dropped or not, whether there is any obstacle on the rail, and whether there is anything dropped inside the pedestal (TEPCO's word in the handout on 8/2/2013).
The rail is there, and there are some items on the rail. TEPCO says they will try again in August 6 to reach inside the pedestal. They will also collect the water sample on August 5.
From TEPCO's Photos and Videos Library, 8/2/2013 (English labels are by me):
The condition of the rail reminded me of the guide rail for the Reactor 3 CV's equipment hatch - some blackish substance, though it could be just water in the dark.
Just like the first video of the inside of Reactor 2's Containment Vessel taken in January 2012, there are constant drops of water in the dark. And radiation:
If TEPCO is successful on August 6, we may get to see the corium for the first time.