So i recently got a GoPro Hero 3 White edition and a Blackmagic Ultrastudio Mini Recorder.
I was having a lot of problems getting it set up and working so thought i would share what i have learned in the process.
It seems that it all has to be set up in a very particular way for it to work.
1. Plug in the Mini Recorder to Macbook via Thunderbolt cable.
2. Set the GoPro to 1080 30fps
3. Connect the HDMi to the Mini Recorder and GoPro
4. Open VDMX and go to the Vid In tab and select Blackmagic capture devices from the drop down menu and then check the Enable button for the Mini Recorder.
5. Change the settings to in VDMX 1080p 29.97
6. Power off the GoPro whilst keeping it plugged in and then switch it on again.
7. You should now see the image from the GoPro in VDMX
Notes: It seems that if you connect the via a Laptop micro USB lead to the GoPro to charge it whilst it's connected to the Mini Recorder the output image switches off so this method can only be used when you know the GoPro battery will last the duration of your show. To keep it powered for longer you will need a wall charger.