Ncap is downloaded and installed if you select to do so during the JMR installation from nmap.org. This is a normal installer and its uninstallation is available from the normal windows Add/Remove Programs widgets. Npcap is and can be used by lots of different network monitoring software, not just JMR.
Major windows updates are well renowned for not reinstalling drivers unless they are distributed via windows update, meaning they need to be reinstalled again. Ie The npcap software was installed but the npcap drivers had been removed, and therefore JMR could not connect to them.
Npcap is open source software I make it available for downloading and installing through the JMR installer and from the settings page. The npcap software installer appears and you progress through their installer to install it. I can't modify it in anyway or include it in inside JMR as it is commercial software.
Getting the prompts you did means that things were pretty messed up due to the windows update applied.
I take your point that the prompt to reinstall JMR, should also include to a message that a reinstall of npcap and/or my own network monitor may also be required. I see what I can do there to make it more clear based on what the errors that triggered the prompt are.
Despite problems with Media Recorder and Npcap, I consider myself lucky in that the 2004 feature update to Windows 10 didn't screw up my computer even worse. I've read the horror stories. When reading the release notes for the 2004 update, there are still lots of problems listed as "Investigating" which means they have not yet been resolved. Microsoft didn't offer me the 2004 update until less than a month ago, and now 2010 ( aka 20H2) is out although its description is that it is mere GUI fluff.
The only other problem that I've run into, so far, is the playback device changed to the digital output which is not used. I had to switch back to the analog RCA outputs. Before I installed the 2004 update, I saved a full backup image as an escape route (System Restore is unreliable hence worthless since it leaves behind a hodgepodge of new and old versus an image backup that gets me back to exactly the same state as before). If I had not figured out how to fix Media Recorder (but the program hinted in a popup to do an uninstall and reinstall) and also uninstall an reinstall Npcap (because I couldn't get Media Recorder to reuse the existing install probably due to the 2004 update breaking the driver as you mention), I was going to revert to the backup image.
Thanks for the help.