Facing TV Problems? Ask a TV Technician.
You will need to add a silent audio file to the video.Because there is no audio on the file, the TV does not know that because it is unable to decode it (since it doesn't exist), so it will always display the message. This is probably a firmware bug, as in theory you should be able to play a video without any audio content if you wish to. The Tv designers obviously haven't thought of their product being used for this purpose!
So for now, you will need to edit the video and add a silent audio file to get around this problem.