I've been looking for an answer to this problem for a while now, without any success.

 

I have a AVH-P4100DVD, with the proper iPod control cables. 5th generation iPod works perfectly. Controls from the head unit; controls from the iPod; playing audio and playing video.

 

However, when I plug in an iPhone (first it was a 3G, and now an iPhone 4) it doesn't play video properly. The audio and video is out of sync. The same video will play fine from the 5th gen iPod, just not on the iPhone. And I've tried 2 different 3G phones, 2 different iPhone 4s, and even an iPod touch. All have the same synch issue. However, the iPod will play it with no problems.

 

Any ideas?