The scanner does not load all the protocol handlers and therefore URLs for remote services (BBC iPlayer, Rhapsody, ...) are not considered remote or valid. Therefore, such tracks in the playlist file are rejected by the (stand-alone) scanner.

Slim::Player::ProtocolHandlers::%protocolHandlers contains the hard-coded entry "rtsp => 1", which would fix this issue for the (obsolete) AlienBBC plugin but this is not a general solution.