While you can't embed a video into your mailing, you can use our video block feature to link to your YouTube or Vimeo video in a slick way.
When in edit mode of your mailing, pull in the Video block from the lefthand navigation. It looks like this:
Drop it onto one of the blue tags where you'd like it to appear in your mailing. The block will immediately open, and you'll add your video's URL and alternate text, which is what will display if images are turned off in a recipient's inbox.
Click Enter or Tab to move out of the URL field and let us grab the thumbnail. Click Insert Video, and you'll see that a play button appears on top of a still from the video.
The thumbnail is pulled from the information that YouTube and Vimeo send. There isn't a way to determine that thumbnail, so if you'd like something different, you can add your video the old-fashioned way, by taking a screenshot of the still you'd like to display and linking that image to the video's URL.
The video will not play in the email; it will link out to your YouTube or Vimeo URL. (Trying to embed a video can make the email a little heavy for the recipient, and some servers will block these types of files from coming through. That can negatively affect your delivery rate, which we never want to happen.)