On v7 and above MMH Servers, Blackmagic cards are automatically installed. Servers on v6 or below might require to install the BM card if it's not detected properly.
Here is how to do it:
Install the Blackmagic files using gdebi or dpkg. Once done reboot, the card will be detected.
You can view the cards status using #BlackmagicFirmwareUpdater status
In case you need to update the Blackmagic card use #BlackmagicFirmwareUpdater update all