As I understand it, a right is a right by virtue of its existence and not grounded on any other conditions, meaning that if we believe something is a right, it exists, whether or not we know it exists and whether or not we have any way to currently enforce it.

A right that is not enforced is not a right at all. It's notable that the 'natural rights' that Napolitano lists in this video are those codified within the constitution and enforced by the United States government. He is talking about legal rights and confusing them for natural rights.

Natural rights are no better than people's opinions. You can say that someone 'ought to have a right', and maybe you can work and get that enshrined in law, but until it becomes a legal right it really is just an opinion. The rights that matter, the ones that people want, are legal rights.