Thanks to the OP for starting this thread - I didn't know you could edit video in PS.
I was able to remove a sensor spot with the clone stamp tool and that worked fine as long as the background doesn't change or move. When it does, I tried to do it exactly as in the video using Dust and Scratches on a smart layer and masking it in as described but it didn't work in CS4 Extended, or at least not for me. Drat - I think it must only work in CS5 and above.