Jellyfin Is completely open source, fully self-hosted, and free. With Plex the software still has to phone home to a central server for authentication and some features are locked behind a paywall.

No streaming software is going to find movies for you (without paying for content they’ve licensed) because that would be a sure fire way to get the project taken down for copyright violation.

I do worry about how the community will handle when that eventually becomes a problem, or how the community might keep it from becoming a problem in the first place. Low-quality posts are inevitable with a sufficiently large user base.