Okay so if you wanna watch a Jellyfin video with VLC, go to your Jellyfin instance’s web view where you can copy a stream URL and it’ll look like this:
https://jellyfinserver.tld/Items/TheIdForTheVideoGoesHere/Download?api_key=YourKeyIdGoesHere
And you can paste that URL into your VLC.
If you want to grab a whole season’s worth of video IDs that you can mangle into a .pls, you can with Jellyfin’s API! Here’s an example using httpie and jq.
https jellyfinserver.tld/Shows/ShowIdThatYouAlsoCanFindFromTheWebView/Episodes X-Emby-Token:YourKeyIdGoesHere season==1 |jq -r '.Items[].Id'
With VLC, watching stream URLs from .pls files is way better than watching individually pasted streams since it can remember how far into the video you were.
Pretty sure this works with other stream players too, like mpd.