Just star the project on GitHub. They have a feed on the startpage where you’ll get notified of releases.

Why put it in the notification about the next video? Wouldn’t it be a better idea to have the favourite button in the player overlay, perhaps in a context menu?

Web applications may have vulnerabilities that allow an attacker to run code on the host system (Remote Code Execution). Famous example would be the log4shell vulnerability.

If you want to expose your server to the internet, you have to make sure you are not suffering damage if an attack like this occurs.

1. Give the server application minimum privileges on your system. Use either containerization, sandboxing or systemd hardening to prevent the app from running commands on your system or access important data. Jellyfin for example only needs to read your media library, so if you are using docker, mount it read-only.
2. Keep both the reverse proxy and the application up-to-date. For a docker setup you can use watchtower.
3. Make backups of both your media collection and the Jellyfin database in case you need to restore your system. You should also have a script or at least some written notes on how you set up everything.
4. Ideally isolate the media server from the rest of your network. If someone manages to put malware on your server, they should not be able to access the rest of your network (PCs, smart home devices, cameras, etc). This requires a more advanced firewall than most consumer routers have, so I currently do not do it on my home setup.

I think they covered it with black foam, because they do not want to reveal what camera they use.