title: Change Video source to blob / ObjectURL
body: <p>I would like to hide a video source's attribute. Therefore I wanted to convert the src attribute of the video's source-tag into an objectURL. It sadly doesn't work.</p>
  
  <p>I already tried</p>
  
  <pre><code>function display(vid){
      var video = document.getElementById("video");
      video.src = window.URL.createObjectURL(vid);
  }
  
  display('video.mp4');
  </code></pre>
  
  <p>(as provided here: <a href="https://stackoverflow.com/questions/14317179/display-a-video-from-a-blob-javascript">Display a video from a Blob Javascript</a>)</p>
  
  <p>That did not work and the Stack is already 5 years old.</p>
  
  <p>HTML Looks like this</p>
  
  <pre><code>&lt;video id="video"&gt;
     &lt;source type="video/mp4" src="video.mp4"&gt;
  &lt;/video&gt;
  </code></pre>