If you’re referring to the old openmls-nostr library that I’d been using previously, it’s dead. I’ll be archiving that soon. If you’re talking about the new one I’d love to know more about what you’re looking for.
Regarding the media stuff. I’ll add details to NIP-EE to make it clear how it’s working. I’m using parts of several already merged nips but the encryption directly uses aspects of MLS.