how to get openCV to read frames from a Blackmagic Mini Recorder?

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What's the simplest way to get an image from a Black Magic Mini Recorder (Thunderbolt connection on a PC laptop) into an OpenCV Mat? Capturing from a webcam works fine though I can't capture from the Blackmagic Mini Recorder.

I'm using Visual Studio 2013, Blackmagic DeckLink SDK 10.4 and OpenCV 3.0.0 I'm quite new to programming so some clear and simple instructions would be ideal.

I've noticed that quite a few people have asked this on the internet but with no answers, so this will surely be a valuable answer to many.