11-26-2017 05:44 PM
It's not easy - the only way to do it in AEM is to mess around with the source code in your browser's element inspector.
But even if you did, it is in poor form to embed a video directly. Most email clients (Outlook in particular, plus everything else) will block any embedded videos and give compatibility issues. You can't play a video directly within outlook, it will always require you to launch a web browser and play it there.
The standard way of adding a video to your template is to take a screenshot of your video as a static image, then add the image to your template, and have the image be a link to your video on the net.
Make sure the video player controls are included in your screenshot, then have the image link to the youtube page. Users will instinctively click on the image of the video to play it where it will launch browser, which is all the same.