I will design a thumbnail according to your needs. Thumbnails are one of the most neglected parts of a video. I often see people using the default thumbnail which usually consists of a snapshot taken from the video that is a little out of focus or shows a person mid-blink. A thumbnail is a small image representation of a larger image, usually intended to make it easier and faster to look at or manage a group of larger images. Graphic designers and photographers typically use this term.