Video
There is no special way to handle videos, but Vimeo and YouTube videos in iframes look nicer if you wrap then in a video-container
class. Those videos have a fixed ratio and so we can make them responsive and full width (of the container - below that means full text width) with a little css.
<div class="video-container"><iframe src="https://player.vimeo.com/video/473377963" width="640" height="360" frameborder="0" allow="autoplay; fullscreen; picture-in-picture" allowfullscreen></iframe></div>