Free Novel AI approach Constantly Updating Picture Set Discreet (ish) App Icon Images only. There are no download or icon changing options though.
Free Chromecast-compatible Integrated Video Player Can Lock App You Need to Pay for Highest Resolution Videos No Integrated Downloads. There are a couple of security-minded features included too, like password protection and the ability to change the app icon.
You can also quickly swipe your way through stills from each video too, which is neat, and all the videos have a low-quality option to help people with slow connections.