It is supposed to look like the following:
The first thought was that somehow the embedded youtube video was causing a problem. It was commented out and, lo and behold, the comment link reappeared. But what could be wrong? The youtube video was the same as any other. The coding was the same, no closing tags were missing.
Blogger puts in the following code whenever one uploads a graphic.
<div class="separator" style="clear: both; text-align: left;">
I put it around the video and now the comment link worked.
Why you need this div around some videos and not around others I haven't figured out yet.