I don't think that's what he meant. Let's say you have a document that you want to share with your friends who don't have an Owncloud account on your instance.

I don't think that's what he meant. Let's say you have a document that you want to share with your friends who don't have an Owncloud account on your instance. You click on share and get a publicly accesible link like "example.myowncloud.com/ji7H2i". I don't know if Owncloud is able to do this, but it works with pyd.io.