If you can’t sync a video
If iTunes tells you that a video wasn’t synced because it can’t be played on your device, you can convert it to a version that’s optimized for your device.
You can convert most videos to work with iPod, iPhone, iPad, or Apple TV.
Convert a video
In iTunes, select the video you want to convert.
Do one of the following:
Choose File > Create New Version > Create iPod or iPhone Version.
Choose File > Create New Version > Create iPad or Apple TV Version.
Converting a video can take several minutes to several hours, depending on your computer and the length and content of the video.
The original video remains in your iTunes library.