iPod Touch 4G Will Not Sync Movies

To start off with, the movies I want to sync are not bought from iTunes, but I did put them in my iTunes library. I hook up my iPod touch to my computer to sync these movies to my iPod touch, but it gives me a message saying the movie was not synced to iPod touch, because this movie cannot be played on this iPod touch. This is new, because I previously have synced a movie to this iPod that was not bought from my iTunes, and I put it in my iTunes library, and synced it to my iPod touch, and it played just fine. I looked into this message more, and it said something about the format of this movie is not supported with the iPod touch, something along that lines as I remember. Only these movies are in mp4 format, and the one I previously synced to my iPod was also in mp4 format. Please help! Thank you. ios 6.1.6