I experimented David laserscanner some times ago and now I was looking for information about the BlackMagic card in order to use full HD camcoders as webcams. I finally found this interesting thread and I'd like to post what I gathered so far.
I asked BlackMagic's support team about the usage of their Intensity Pro card and in particular if it comes with a WDM driver, but they told me that there is no WDM driver available. On the other hand, they said that their drivers install a DirectShow filter (I am not an expert but, as far as I know, this does not imply that there is also a WDM driver under the hood...). Then I asked if it was possible to use for example AMCAP with their card and they told me that they have news about some of their clients that are using it with AMCAP as well.
So, I guess that it may or may not work...and I look forwar to reading about superrune's tries