Ok perhaps we need to define what an extra output is. I have had the BM box running as my video output (instead of the hdmi out in the mac) to my projector. This worked fine until I updated to silicon mac. I have notbyet bought the new usb-c version so cannot say if it works.
What we are suggesting is that the studio should setup 2 identical hdmi enabled monitors with ideally identical delay. Also get the BM hdmi output device and split that signal to both monitors. (How to split is already explained). Test sync with beep and countdown and set delay for the whole chain.
Voila
Then both the talent and the engineer can watch the sync video output from nuendo.
It is not exactly like in Premiere, it is better though because the engineer sees the same video in sync.
What this box won’t give is another desktop screen output.
I hope this clears things up.