How do I change the video in a side-by-side video element?
The editor panel contains an element that puts a text block beside a video.
Drag the block onto the page to insert it onto the field.
To customize the video open the Settings dialog for the element and chose the Customize panel, then click on white space to the left of the video to release it (you can't click on the video itself since this will trigger the player).
The Video tab lets you choose to preview a video hosted on either YouTube or Vimeo. In each case just enter the movie or video id, not the full URL of the video.