Excellent for finding vertical versions specifically tailored for iPhone and Android lock screens. How to Set It Up
Use Wallpaper Engine ($3.99 on Steam) for the best performance and lowest CPU usage. If you want a free alternative, Lively Wallpaper (available on the Microsoft Store) allows you to turn any YouTube link or video file into a background. On Mobile: Anime Burning Sky Live Wallpaper
A great free resource for looped anime backgrounds. They have a specific category for landscapes where burning horizons are a common theme. Anime Burning Sky Live Wallpaper
Use "Video Live Wallpaper" apps to set any .mp4 file as your home screen. Anime Burning Sky Live Wallpaper