title: ".playVideo is not a function" when trying to play youtube video javascript
body: <p>I'm trying to play a youtube video with javascript and the <code>&lt;iframe&gt;</code> tag. So far I'm getting this error: "document.getElementById(...).playVideo is not a function". Here's my code:</p>
  
  <p>Javascript:
  <code>document.getElementById("video").playVideo();</code></p>
  
  <p>HTML: 
  <code>&lt;iframe id="video" src="url"&gt; &lt;/iframe&gt;</code></p>