Supports MP4 and WebM format.
Max image size 5MB, (due to browser local storage limits).
Take care with large files, they may impact performance.
Add more than one URL separated by spaces or on new lines for a random background image on load.
Unsplash can be used for random images, eg:
https://source.unsplash.com/random/1920x1080/?night,day,sky
Change parameters after .../random/ for more options. Loading times may vary.