I can see why a company would want to make a video auto-launch since out of all those who receive the link, a sizeable number will elect not to click on it. One issue would be where the message is viewed. For example, will some customers open the message on a phone or tablet? If so, what would be the universal player found on every phone and tablet? Also, some desktop email clients don't auto-launch HTML5 or a video in GIF format.