John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
Videvo - Free HD stock footage & motion graphics for any project!
Wallcat - Enjoy a new, beautiful wallpaper, every day.
Coverr - Beautiful free stock videos for any use
Splashy - Breathtaking, auto changing wallpaper app for macOS, Windows, Linux, iOS & Android
Mixkit - High-quality stock videos that are completely free.