Click On Facebook Button To Download Content

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Hi,

In our shop we offer a lot of free educational materials to download. Files are linked in products and customers can download from the product pages.

I'm looking for a module or functionality requiring customers to click on Facebook button to social share the product in order to access the download. Since it is totally free, at least we got a Like.

I found this payment module that has nearly the functionality I'm looking for, I am not totally sure:
http://catalogo-onlinersi.net/es/noticias-y-anuncios/297-compartir-para-mostrar-contenido-oculto.html

Do you know any similar module/functionality to make customers like content befor access it?

Thank you very much for your time!