I have a 10 TB mirrored NAS setup for stuff like this. I have to curate what I put on it as eventually I will be out of space and I do not want to make a lifes

I have a 10 TB mirrored NAS setup for stuff like this. I have to curate what I put on it as eventually I will be out of space and I do not want to make a lifestyle out of it ;) My criteria is: Will I want to watch it again? Will it go away forever? (Or is at risk of it) Can it just not be streamed or purchased in my region? (Yes there are some things)