Was the problem w/ Fusion 5.3 and Blackmagic ever fixed? I found this post dated May 2009 querying "fusion" in the forum archive. I still experience this issue...
Actually Decklink drivers don't work with Fusio 5. If you open the panel in Fusion prefs it crashes. It's a known issue and BMD knows it. They are working on it. Here is part of the email i received:
Currently there is a bug with Fusion support and it is currently not
working. There was a big change in the code to accommodate a bunch of
different things and one of the unforeseen side effects was that it broke
the Fusion support.
Center City Film & Video