Displays a Youtube video.
Example:
<amp-youtube
data-videoid="mGENRKrdoGY"
layout="responsive"
width="480" height="270"></amp-youtube>
With responsive layout the width and height from the example should yield correct layouts for 16:9 aspect ratio videos
data-videoid
The Youtube video id found in every Youtube video page URL
E.g. in https://www.youtube.com/watch?v=Z1q71gFeRqM Z1q71gFeRqM is the video id.