A video is usually presented to users with a video cover thumbnail as well as several (up to 8) additional thumbnails that give the user more information about the video.
The amount of these thumbnails depends on the skin selected during the creation of your site.
By default the system selects thumbnails generated for the video. However, you have the opportunity to change thumbnails to ones that you prefer.
5. You can delete one or several thumbnails from the "Current Thumbnails" section by clicking on the x in the top right corner:
6. You can change them by clicking on the thumbnails in the "Timeline" section:
A thumbnail can only be selected once, and selected thumbnails are highlighted in white:
7. Click "Apply" to confirm your changes: