Minor update, I edited my original comment above. The app does seem to work with Jellyfin 10.11.1.

Maybe I'm not the best test candidate LOL... I usually use the Android Jellyfin apps for music so my original test was with a Jellyfin user with only music libraries enabled.. Findroid does not like that apparently. Once I logged in with a user with TV/Movie libraries enabled it seems to load and play video.