Edited to clarify.
Things to consider: How much of your data would you be comfortable letting Lemmy sell vs Reddit? If Zuck treated users better, would you be more accepting of Meta monetizing your data every way possible? When it comes to using something for free (tangible or intangible) do you accept a company selling your personal information if their practices align with what you feel is fair?
Jellyfin is more like a self hosted streaming service for movies and shows. It can only watch content you provide yourself on your server, with that content coming from fully legal sources.
So it’s akin to Plex.
The comparison the comment I replied to makes no sense then.
YouTube -> JellyFin is like comparing Amazon to owning an empty warehouse.