You don’t actually need a NAS. You can install in an old hardware you have and it will work just fine.
However things may become short in space quickly, cause video needs a lot of storage. So if you want to host many video files, I would recommend at least high capacity HDs. A NAS would be the perfect setting, but not always we can do perfect settings.
What I suggest however, is to be sure that your network settings (router, mainly) support streaming, cause if your router sucks, you’ll not only become frustrated soon with the streaming, but all your connection with internet in general may become degraded.
Also, you can start small, with a small server with internet HD, and then adjust and implement NAS in the future. It’s an easy task.
You may wanna take a look at Jellyfin as well
Can’t you backup your database?