Yeah, I actually did a write up of the roadmap recently, it is here: https://mattiasgustavsson.itch.io/yarnspin/devlog/522668/yarnspin-v20-dev-update
Sound and music is already implemented, and will be there in the next release (it is already in the source code on github).
I don't think I will be able to add movie playback, the code for that is very complicated, and all the libraries I've seen for it are way too bloated to fit Yarnspin. I am planning to add support for animated gifs though, and I have been contemplating some sort of simple sequencing commands to make cutscenes.