The app doesn't work on some VPN

[ccgauche]

Youtube API seem to be blocking unauth downloads from VPN IPs.
This could probably to bypassed through proxies or inject the same cookies as for the API.

The idea would be to detect that the video is set to private. In this case show a popup with written:

• A video is tagged as private
• Do you want to use your connection cookies to download musics
• A toggle for remember this setting
• Or a dismiss