If you run out of graphic card outputs and still want to use your video monitor/projector that is exclusively connected to a Blackmagic card outside Nuendo, Premiere, Vegas, final Cut or Protools, it is a no go.
The Blackmagic Intensity pro doesn’t have the driver to be run with a plain windows player.
I found this little gem called DLVPlayer. It allows you to play videos outside Daw and NLE sotfwares.
There’s a demo for it. It works perfectly on my system. It is windows only.