Thumbnail is low resolution image that is generated at consistent intervals throughout a video. Viewers will be able to see these thumbnails scrubbing through a video.
Thumbnail cannot be viewed when scrub through a video.
1. Unsupported flash version.
2. Processing error.
RESOLUTION 1 - Unsupported flash version
Using unsupported flash version results in disappearance of thumbnail images when user refresh the page. Make sure you have the latest flash version. The supported flash version is 10 or above.
RESOLUTION 2 - Processing error
Some times, failure in processing may also result in thumbnails missing. A quick fix would be to delete and re-upload the video. If the issue is still present, please create a support ticket.
* There is no standard method to set a default thumbnail size on the API. However, you can use the "resolution=widthxheight" parameter in your query to retrieve the image in the expected size.
* Ooyala automatically generates thumbnail of width X and X/3. X is the width of the source video.