This problem is usually the result of a faulty video codec.
To correct the problem temporarily, reset the power to the LED sign. Once the sign restarts, your videos should start playing.
To fix the problem from happening again. You will need to test each video using a different codec one at a time. This can be done by clearing all videos from you sign, keeping all text, time, and temperature. Then adding one video format to the playlist. Test that playlist over the next day or two to make sure it doesn’t stop playing. As soon as you come to a video format that stops playing, record which videos you added last. If they all have the same video codec, then you can identify that codec as the problem. You can try to re-install the codec, re-render the videos, or try another codec for compression.