I have an asset library to store videos, but the videos have no sound when are reproduced and the sound button appears with an X and cannot be toggled. If a download or save the same video in another library it can be reproduced without any problems and sound perfectly. I've updated silverlight but didn't worked.

Is there a fix for this?

Edit: If I save it on another document library when it opens use quicktime. And the video is MP4.

David