How to place a promo video from YouTube or Vimeo in a form? To do it add «Video» option in settings of block with a form, insert a link to a video in a relevant field. Turn on autoplay for a user by ticking a flag in «Autoplay» field if needed.
When adding a video from Vimeo, you need to specify a private hash attribute for the video. This attribute can be found by clicking on the Share button on the Vimeo side, and copied from the code.