In this context ownership merely defines who has the right to be the seller in a transaction. As far as I understand this, blockchains don't handle the issue of duplication, where it doesn't matter who has the rights to begin a transaction - anyone can still access the bits.
For something like currency which is entirely defined by its ability to be used in transactions then the application of blockchain to define ownership is obvious. For something like media, where ownership is not just transactions but also access, it isn't obvious to me at all.
In other words, blockchains and smart contracts handle authenticity of a piece of data when used in transactions. That's valuable for data that is defined by its ability to be transactional. It's not necessarily valuable for data that needs to be more than that.
I would also contend that it's not secure by all definitions.