Videos inside Popups should honor the autoplay attribute. Samples, that currently do not autoplay:
Custom Video / Video-Background in Divi Section:
<video autoplay><source src="video.mp4" type="video/mp4"></video>
YouTube:
<iframe width="640" height="360"
src="http://www.youtube.com/embed/M7lc1UVf-VE?autoplay=1"
frameborder="0"></iframe>
Vimeo:
<iframe width="640" height="360"
src="https://player.vimeo.com/video/76979871?autoplay=1"
frameborder="0"></iframe>