Have you ever. Been able to sync a digital copy to your phone before?
Could be a copyright error of some sort. Happens with music a lot that isn't purchased through iTunes.
Try running it through another program first then to iTunes. Try handbrake.
Then you use iTunes 64 bit, Use google on how to backup you iTunes media folder. uninstall iTunes, reinstall iTunes with iTunes running under file in iTunes use add folder to Library on your backup iTunes media folder. If you need more info on this google hoe to reinstall iTunes. Also Quicktime is another program from Apple to play movies in iTunes.
Start iTunes, connect your iPhone by USB cable. Once iTunes recognizes your iPhone, click on your phone (left side column) select the Movies tab. Check sync movies and select the movies that you may have gotten a digital file in 264h format and is displayed in iTunes. Any other movie files you will need to google on hoe to convert them to 264h and adding them to iTunes.