Hey, it worked, just fine. Many thanks!
A quick step-by-step, for anyone else wrestling with this task -
1. I DL'd the HVEC extensions, directly from the Microsoft store, no cost. Before I even left that webpage (Firefox), the screen told me it had installed those extensions (presumably, machine-wide).
2. I then DL'd the K-Lite codec pack, which is an *.exe file, and ran it. Had to pass through half a dozen screens; just chose the most logical and/or default choices. And, I didn't know what to do with the "Codec Tweak Tool", so I left all settings at their original installed values.
I saved a number of screen-grabs, as I was installing the K-Lite pack, and I'd be willing to post them, as jpg or similar files, if allowed, so that anyone can make any recommendations on the best settings.
But, no real need for that. I'm happy!
BTW - I located and downloaded some videos, and stored them on an M.2 NVMe chip/drive, for fastest/best performance at 60 frames/second. Haven't yet tried any on a standard SSD drive, or a spinning internal SATA drive.
And, Bandicut is the best "lossless" trimming/splicing program I've found, for isolating and saving (and splicing) segments I want to see again.