iPad Movies won't play; used to play fine.

On the iPad, which is totally up to date, I am using the TV app and the list of movies to play have an indicator on the right side of the screen. If the indicator is a vertical rectangle with a check mark inside, the video plays fine. If the indicator is a right arrow; it will move to the video and immediately move back. Many of these videos have been in my library for years and I can't figure out how some work and some don't. I tried converting some of them, which were in the .m4v format to .mov, and that didn't help.

These are things that I have pulled off of television, using an Eye 3 system so I can put cartoons and even commercials on the iPad for my grand-daughter.