title: Warning: <link rel=preload> must have a valid `as` value
body: <p>When trying to <code>rel="preload"</code> a video file using a <code>&lt;link&gt;</code> tag in the <code>&lt;head&gt;</code> I get a warning in the Chrome console stating:</p>
  
  <p><code>&lt;link rel=preload&gt; must have a valid `as` value</code></p>
  
  <p>My tag is:</p>
  
  <p><code>&lt;link rel="preload" href="https://storage.googleapis.com/[myFilePath].mp4" as="video" type="video/mp4" media="(min-width: 768px)" crossorigin&gt;</code></p>