If you are using a recent version of Safari web browser, you’ll notice that some videos will not play. This is true not just on one site, but on all sites that embed videos. Here’s the fix:

The problem with videos is a “feature” of Safari. The recent versions have autoplay turned off.

To fix it, visit the site where the video will not play.
Under the Safari menu in the upper left of your screen, select “Settings for this website…”
Click the dropdown next to “Auto-play” and choose: Allow All Auto-Play.