So far, apart from some minor bugs which mostly didn’t affect me, things have been working perfectly - so much so that it’s kind of surprising really. Kudos to Marcin (and my thanks for being so engaged on Mastodon when I had questions!)
Does using it as a library obviate vhs?
It's published up at https://github.com/rmccue/cinemastream if you're interested in trying it - it works, but still very early days, as it was just a holiday side-project. That said, likely to become a production tool for work, so will be cleaning it up a bit soon and squashing some bugs.
Worth noting that asciinema is not directly usable as a crate currently, so I did need to fork it to add a lib.rs, but the code was so well-structured that there's not much to do there: https://github.com/rmccue/asciinema/blob/rust-lib/src/lib.rs - Marcin did say he's open to it once 3.0 stabilised though.