Video answer: Fixed: image not showing (or incorrect) when sharing url on facebook
Top best answers to the question «Why no image on my shared youtube video»
When the link is a YouTube video, the thumbnail is a single frame which you can click to play the video. Without the thumbnail, the video won't show up. Therefore when sharing a YouTube link, deselect the check box labeled "No Thumbnail" under the status update box to ensure the video shows up.
Video answer: Why i shoot my youtube videos in the store room of my home