No, you cannot download thumbnails from private or unlisted video clips applying our thumbnail grabber. Our YouTube thumbnail downloader only functions with publicly available video clips. Private or unlisted video clips have to have appropriate authentication which can be further than the scope of this thumbnail extractor tool. Our mission https://spencerolgdc.theobloggers.com/44918352/helping-the-others-realize-the-advantages-of-youtube-thumbnail-downloader