I recently shot and produced a demo for a Professional Seminar speaker and then made him DVD copies etc. I also sent him an iphone version directly from Final Cut pro the editing software I use in all post production. Funny thing is the music played all the way through but his voice was lost after it was synced to the iphone from itunes. You can hear the music thru the little speaker but not music and dialogue. If however you plug in the headphones you can hear both mixed down tracks perfectly.
I have been searching for a cure to this. The first is just up load it to youtube and play it on iphone there. The 2nd is to send the edited piece as an email file and play it off the email.
Either way you can get around the iphone import glitch and I will keep looking for the real solve online. I have left questions in a few forums so perhaps a RT solution will present itself.
The Bensleygram 