You may be overestimating your requirements a bit. For video, all you need is something with a transcoder and it could handle at least one stream. If this is just for you, it’ll be idle most of the time. As long as the hard drives have good reviews, it’ll be fine.

What you listed sounds good. I have my entire family’s files and photos (with some duplicates that i never removed) and it comes out to less than 1TB.

I think your idea sounds fine. An old PC will do fine.