Many answers about using the Youtube Data API v3 to get the thumbnail of a playlist; and many answers for how to get or set the thumbnail of a video.
But none about how to set the thumbnail of a playlist. The documentation shows nothing and no searches into the API documentation or Stack Overflow find the question or its answers.
I tried using the thumbnails().set() method for setting thumbnails to videos, but that returns a permission denied error indicating that using playlist IDs in its request for video IDs is not a good monkey patch.
Please help.
My original question is invalid.
YouTube allows users to set thumbnails of videos to be any properly formatted image. YouTube then only allows users to set a specific video thumbnail as the playlist thumbnail. It is not possible to set an image as the thumbnail of the playlist unless it is a thumbnail of a video in that playlist; and in that use case the video is associated to the playlist for the representative thumbnail.
Q: set thumbnail of a playlist?