This question is related to this one Copyrights of material that would be used for both commercial and non-commercially.
I am developing mobile app that contains ads and premium paid option. In short, it is a commercial app. I want to give the ability to my user to download and listen to materials that was licensed as non-commercial use.
My question is: Is giving the ability to the user to download those materials from their original source via the app and listen to them via the app violate the non-commercial use condition? I mean I will not include them by default and will not advertise that the app contains those material when downloading/buying it.
If it was OK, does hosting the files on my server change the answer? (Keeping in mind that I will put all information about the original materials and to who it belongs and the original link)
Based on the answer to my previous question (Copyrights of material that would be used for both commercial and non-commercially), I suppose that this question will get the same answer. However, my concern is that why it is OK, for example, for commercial web-browser to be used to navigate, download and listen to such non-commercial materials but it is not allowed for the app I am developing to do the basically the same. The materials are not included by default and the app does a lot of other things that is not related to those material. However, downloading and listing to those materials is optional and up to the user request.
I just want to be clear that I am not trying to avoid buying a commercial-license but I found no way to get in touch the owner/owners. Furthermore, there are tons of app and websites that are redistribution those material freely and putting ads or charging the user for the traffic. The owner/owners seem not interested in suing anyone but in the same time did not clearly stated that the materials are for Public Domain and I want to stay in the safe side.