After selecting to use a video as the background of a block, you may choose to apply a video from your WordPress Media Library of uploaded files, or you may choose to use a video posted publicly on YouTube or Vimeo.
See below for details about using either option:
Video uploaded into WordPress
Video from YouTube or Vimeo
YouTube: autoplay, loop, and more
Vimeo: autoplay, loop, and more
Video size & position
Video backgrounds are centered vertically & horizontally. They are sized with cover behavior so that they are scaled to fill the width & height of the browser.
Some cropping of the video may occur at certain browser aspect ratios.