David Dehcbad25 and whoever else reads this follow-up:

Thanks for your input. I just now (it's only 20 minutes since my initial post) discovered that my pop-up ad blocker was malfunctioning. The way it works normally is that when I want to play such a video, I must click on the link button while I simultaneously hold "shift" or "the ctrl key down. That has always worked in the past. I know this was the problem because when I disabled my ad blocker, the videos played just fine.

John