Ignore IPv6 settings value if it’s invalid

This would otherwise cause the backend to always believe the requested host was local

Fixes #12172
Don’t attempt to play the video streams for mp3, flac, off and m4a container.

FFmpeg incorrectly detects the artwork in those file as MJPEG, which myth would then attempt to play.
A nicer fix would be to display that image instead.

Fixes #11597