Colin, forgive me for bringing this up so many years later, but I tried these instructions using the Offset, Circle and Calculations effects to remove lens dust spots from a video clip and it left me with just a black screen. Has anything changed in those effects in CS6 from when you made this post (2009)?
There are a handful of tiny white spots, but visible in the mostly dark video. There is planty of movement in the 15-minute shot.
Also, is the 'digital concealer' preset usable in CS6? How do you install it? Where does it go?