Problems syncing a video in iTunes on Mac
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.
In the iTunes app on your Mac, choose Movies from the pop-up menu at the top left, then click Library.
Select the video you want to convert.
Do one of the following:
Choose File > Convert > Create iPod or iPhone Version.
Choose File > Convert > 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.