Hi,
From what I understand, the Hero 5 Black has HDMI output via an adapter. I'm using a Hero 4 Silver, which has the smallest HDMI output. Once you get the adapter, I think you're in the same boat. 
From there, it will output the HDMI signal perfect and without the overlays if you turn them off in settings. 
To get them into your machine, however, you are going to need an HDMI to USB 3.0 converter. A very popular one is the first link below, but I found the second option to have identical results hardware-wise and is half the price (and only very slightly bigger):
https://www.amazon.com/gp/product/B00I16VQOY/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B071HHSTYM/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
I ended up keeping the second since at half the price it seemed to make more sense for me. 
Either box does introduce a small amount of latency, but overall they seem to be the best way to get HDMI sources into your computer without actually dropping in an expansion card into a PCI-e slot (if you're even using a full PC to begin with). 

Hope that helps!

John
 

John,

 Many thanks for providing the information and advice. Great stuff.
Cheers
Rick