You could potentially get around the copyright policy by putting a disclaimer that the user most 'own' or have permission to grab the images. It's no different

You could potentially get around the copyright policy by putting a disclaimer that the user most 'own' or have permission to grab the images. It's no different than someone downloading a copyrighted picture and uploading them to another service. The other big issue I can foresee is that most of the sharing websites don't have api's for you to programatically get at photos. They in fact do their best to prevent you from ripping photos. You would have to play a pretty nasty cat and mouse game there.