I don't think that's the right test. The question is do you control it? Can it be modified? Can it be defended? Transferred or loaned to someone else? Copied?

I don't think that's the right test. The question is do you control it? Can it be modified? Can it be defended? Transferred or loaned to someone else? Copied? The movies and TV on streaming services are not yours because you don't control them and they can be removed at any time. Market salability is another question entirely. There are items you can own you might be prohibited from selling on an open market, such as a landmark property or a particularly destructive weapon.