iPhone and A/V Sockets

My 2006 X5 has the BMW supplied sat nav with integrated TV. In the back there are 2 sockets marked a/v in and out. These are supposed to be for headrest mounted TV's (a/v out) and video/dvd players (a/v in). Has anyone connected an iphone to the a/v in to play movies via headrest mounted screens? If so what cables did you use and did all the audio and video work correctly. Any suggestions for headrest mounted LCD (in the UK) would be useful also.