If I’m in a meeting, I should be able to share a link in the chat to a particular post on my blog, then select the paragraph I’m talking about and have it highlighted for everyone. Well, now I can.
And you could go a few feet farther if you added fragment support to the site, then the browser would also autoscroll to that part. Then you could add a confetti cannon to the system and have the page rain down confetti when more than three people have highlighted the same section!
Transclusion would make this whole scenario quite different. Let's imagine this again...
Many in the IndieWeb have already prototyped this using some open web standards. It's embodied in the idea of media fragments and fragmentions, a portmanteau of the words fragment and Webmention.
A great example can be found at https://www.kartikprabhu.com/articles/marginalia
This reminds me that I need to kick my own server to fix the functionality on my main site and potentially add it to a few others.
This selection tool has nothing intrinsically to do with annotation. It’s job is to make your job easier when you are constructing a link to an audio or video segment.
I'm reminded of a JavaScript tool written by Aaron Parecki that automatically adds a start fragment to the URL of his page when the audio on the page is paused. He's documented it here: https://indieweb.org/media_fragment