Here is a link to a comment I made to myself.
The comments are easy to record. Just click on the lemon icon floating about on the screen and a recording tool will pop up along with a cool cursor with a blue comet tail on it. You can scroll up and down within the post. You only get three minutes, but that is quite enough to make a quick comment.
The comment gets sent to your email and you can go to Zest site and view it there.
Lots of adjacent possible play here with this. I love the idea of screencast comments. I sure wish Hypothes.is has this capability.
Here is a Lumen video I used to promote the Zest tool.