It would indicate the mp4 format on the other 5 was not done properly, or some copy protection in the original files caused it when converting to the mp4 format. For those type of situations, you use a video capture program like RECORDMYDESKTOP or CamMedia to record it's output rather than using a conversion program.
I had loaded 10 movies on a USB drive to take to a friend's house to watch. Only 5 of the 10 displayed. They were all mp4 files and my thumb is formatted to FAT32. Why wouldn't the other movies display? Any help appreciated. The TV is a Samsung but not a smart TV.

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