Sony contacted Polygon after they released an article about how people that are 18 years or older with sub account, can upgrade to a master account, saying that the info Polygon gave before wasn't true. Here's the article, you can see it talked about at the end of the article. http://www.polygon.com/2013/11/12/5094136/heres-ho
Yeah, there is even a setting in the parental controls of the master account that should enable sub accounts to use the Share functionality, but sadly it doesn't do anything. Shame that they automatically block it instead of giving us the choice.
They need to fix this already, had some awesome footage on Killzone multiplayer and I can't upload it. They will even make more money because if they let sub-accounts become master accounts then all of those subs will need to buy PS+.
Actually sub accounts can get PS Plus, I think that you are only limited to getting 1 year instead of 3 or 1 months unless they changed it recently. My sub account has PS Plus and if only one account has it, you can make it primary and anyone that plays on your PS4 can enjoy the benefits without having to buy another subscription. Agreed, a lot of great footage that I would love to upload or livestream, but can't.