SOLVED: All new videos won't play anymore

[TheDreadPirate]

I responded in your other thread.

Regarding the solution in this thread, TLDR; it doesn't apply to the latest versions of Jellyfin. Due to a security issue in ffmpeg, we removed the ability to specify a custom ffmpeg path in the Jellyfin dashboard UI. There are other ways to achieve the same result, but we purposefully made it harder for security reasons.