If your display or player stops displaying content after you update your posts, you need to proceed a primary diagnosis of your device's content.
Log in to CMS, go to the Live Monitoring page and open the device detail:
Content check at the bottom of the window:
Click the button to check the content - to check the availability of all media files, images and videos. Files that are not available are listed on the Errors line:
If missing files are listed, search for them in the Media Gallery and edit / re-upload the missing files to your posts: