I added a thumbnail image to a video and to a playlist, then changed my mind. 
Please could there be a way on PeerTube to delete the thumbnail image after it has been inserted, so that the video goes back to not having one?
Another issue is that playlist thumbnails get truncated if they are not to an aspect ratio PeerTube requires. (i) The required aspect ration is not mentioned and (ii) there is no way of cropping the thumbnail image after it has been uploaded.
It would be grate if these issues could be resolved on a future update of PeerTube. Thanks guys!