LINK: https://worldlanguages.github.io/animatedThumbnailsBookmarklet/ Press space to see the second slide. Might not work in Safari, iPads or old Edge versions. You can also upload static PNGs with this. I noticed some people do not like doing drag and drop or having to go to my profile each time they want to set a thumbnail. That's why I've made a bookmarklet with extra functionality, like upload progress, thumbnail preview, ability to use the file picker, and more. Enjoy (:
