Can you confirm that you're running the most recent version of your BlackMagic software?
Running the latest in everything. By the way I still have FCP on my system and scrub on that works, scrub also works in AE.
I have contacted BM and they have told me that there is currently no scrub implemented for Prem CS5 on a Mac.
Maybe the next update they said
I have got the same problem. is it fixed in CS5.5?