Hi there, my name is James and I would be happy to help you today!
Have you tried accessing the video files on your computer by transferring them across from the camera?
the reason I ask is because the data may be corrupted on the memory card, and may need to be formated (All files deleted)
if you can get the videos to work fine on your computer, I would suggest copying them across to your computer so that they are safe, and then go ahead and format your memory card, take a couple of test videos with the fresh card and verify that everything is working correctly
and then move the video files back to the card and test again
you could have 1 file that is the culprit, or you may find that this process fixes the error regardless :)
I will await your response until you can test this out for me
and thank you for using Justanswer today :)