This how-to video was created by Matthew Neer and it does a great job of showing you how to add a video from Youtube to a post or page in WordPress with autoplay and without the usual Youtube controls. Having a video set to start on autoplay is a must for things like video sales pages.

By removing the Youtube controls from the video you lower the chances of your visitor leaving your site to go watch more videos on Youtube. Among other things this technique completely removes the related videos portion of the Youtube embed.