title: Crossorigin errors when loading VTT file
body: <p>I'm new to using the audio tag in HTML 5 and wanted to build a player. I wanted to test using a VTT file in a track tag to see how closed captioning could work.</p>
  <p>Here is my code:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;audio controls&gt;
      &lt;source src=&quot;myaudio.mp3&quot; type=&quot;audio/mpeg&quot;&gt;
      &lt;track kink=&quot;caption&quot; src=&quot;myaudio.vtt&quot; srclang=&quot;en&quot; label=&quot;English&quot;&gt;
  &lt;/audio&gt;
  </code></pre>
  <p>According to what I've read, track is supposed to work for both audio and video, which makes sense from an accessibility stand-point. What doesn't make sense is the error I get trying to load it:</p>
  <pre><code>&quot;Text track from origin 'file://' has been blocked from loading: Not at same origin as the document, and parent of track element does not have a 'crossorigin' attribute. Origin 'null' is therefore not allowed access.&quot;
  </code></pre>
  <p>When looking up the crossorigin attribute, I get a lot of confusing articles about CORS and the expected values of &quot;anonymous&quot; and &quot;user-certificate&quot;. Trying either results in a similar error.</p>
  <p>Any ideas as to why this won't work?</p>