This is an awesome tool, and I love to see it get a Rust rewrite.
But the one thing I really wish it could do is embed properly in GitHub's markdown UI so that when I click them in READMEs it doesn't have to send me to the asciicinema site.
I'm sure that has way more to do with GitHub than it does asciicinema, but still, that's why I don't use it for my projects. I hope that can change one day.