I recently saw this at the Guardian and loved it! They are letting you know that content is not free and then requesting KINDLY that you help support them either by becoming a supporter or contributor. It’s a great idea to encourage your visitors in any way possible to help support you in multiple and creative ways!
Might be cool to also have a useful tool that they could use to improve their interaction with their content as well as share with friends. The goal is to make it easy and worth while to share with others!
Great job @guardian!