iPhone and iPad cannot play back some shared videos.

I have a 3rd gen. iPad, an iPhone 4S, and a 17 inch MacBook Pro, all with the latest OS and software. I have library sharing turned on on the MacBook, and an extensive video library of TV shows purchased on iTunes. Some of the episodes, usually from the same season, will not play back on the iPad, and cannot be listed on the iPhone. All of the files are located in sub folders under the same "iTunes Library" folder. They all have the same .m4v file extension. I cannot see a pattern that might help me figure this out, so I am asking for help.