What should I do If YouTube does not return video thumbnail?

If there is no thumbnail available for your YouTube video, Google returns default, blank image. There are a couple options to fix this issue:

• If you own the video, go to YouTube Video Manager and set a custom thumbnail.
• Set a poster image in YouTube Showcase. YouTube Showcase, by default, displays the video's poster image first.
• Try another thumbnail resolution for the video by selecting lower or higher resolution using Video Thumbnail Resolution field in video edit screen in WordPress Dashboard.

Please note that if YouTube returns multiple blank images, it could be time consuming to fix them manually. In these cases, you can use Operations button in the video list screen to start CSV Importer/Exporter. You can then export your videos to a CSV file, set the thumbnail resolution for the videos using your favorite (Google Spreadsheet is recommended) spreadsheet and import them back using the update option in the import screen.