I don't have it anymore, but I did a live coding session in ed(1) where I edited thousands of lines of XML code as a demonstration of using ed. It's a very powerful editor, almost too powerful for my "simple tools" aesthetic.

Just a few things you can do with Ed:

Structured/Outlining Refactoring Rapid code catenation and splitting

It's one of my favorite editors. I don't think I have a video of it, but prior versions of the code were optimized for ed(1) hacking, allowing me to do structured/outline editing easily with ed(1).