NOTE: This answer which doesn't address the Remote Desktop Services licensing issue.
As I was investigating this, I noticed the following:
Windows 10 Pro works just fine
Windows Server 2019 supports webcam transport too, as long as I install the RDS service, with the same licensing issue I mentioned
Windows 10 Pro and Windows Server 2019 have a Group Policy entry that Windows Server 2016 does not:
Location:
- Computer Configuration -> Administrative Templates -> Windows Components -> Remote Desktop Services -> Device and Resource Redirection
Name:
- Do not allow video capture redirection
Requirements:
At least Windows Server 2016, Windows 10 Version 1803
Description:
This policy setting lets you control the redirection of video capture devices to the remote computer in a Remote Desktop Services session.
By default, Remote Desktop Services allows redirection of video capture devices.
If you enable this policy setting, users cannot redirect their video capture devices to the remote computer.
If you disable or do not configure this policy setting, users can redirect their video capture devices to the remote computer. Users can use the More option on the Local Resources tab of Remote Desktop Connection to choose the video capture devices to redirect to the remote computer.
The description seems to hint that I need version 1803 of Windows Server 2016 for this to work.
The Internet says 1803 is a core-only release (no GUI), and one cannot update to it from 1607.
I do not know what Windows 10 has already that Windows Server does not until RDS Session Host is installed.