Through an ever-so-graceful slip on the keyboard, I deleted the Downloads link in the 'My Computer' section in Nemo. No idea how to create a link there, though I'm able of course to create a Bookmark to it. But, moving between different computers I get a little aggravated having to remember where the Downloads link is. Anyone care to offer some ideas? Thanks so much in advance!
Found it a few seconds after posting the question. After having created a Bookmark to the Downloads directory, in Nemo open the Bookmarks menu, select Edit Bookmarks (or Ctrl-B). I was able to drag the new Downloads link to the 'My Computer' section.
Apparently there are a few kinks in this process. Somehow my Videos link was in my Bookmarks section. When I tried to drag it above the divider in the Bookmarks editor, it still ended up in the top of the Bookmarks section. So I dragged it above the Pictures link, and the Pictures link became a second Videos link; I had to edit the duplicate to get my Pictures link back.