I'd like a way to set the primary thumbnail image to the current frame during playback in the web interface.   I have a library set to content type "Home Videos & Photos". Emby does a pretty nice job choosing a frame from each video to use for its primary thumbnail image, but sometimes I'd like to choose a different frame.   I can do this manually by playing the video, taking a screenshot, choosing "Edit images" from the "..." menu, clicking the "+" button, uploading the image, and selec