Thanks. I will check out okhttputils then. I don't want them to be downloaded, only streamed(although I know that everything accessible on the web is downloadable).
But for this it will will save bandwidth, it's not a real "unlimited data" plan, there are limits. Because as a user does not like the song they can stop listening an not the whole track is downloaded first, also they don't have to wait downloading and start listening instantly.
For now it works without protected folder. So hopefully it works with your suggestion. (and I will take the download as next option in consideration).