title: Javascript video blob and progressive download
body: <p>Trying to switch my video streaming web application from using classic <code>&lt;video src="http://myserver/video.mp4"&gt;</code> with URL to <strong>blobs</strong> to avoid a full download on a simple Ctrl+s on the page.</p>
  
  <p>Use of XMLHttpRequest seems mandatory to allow creating the blob from the distant video file.</p>
  
  <p>Problem is XMLHttpRequest download the whole file, which is not usable for progressive download use.</p>
  
  <p>Following code is the simpliest example to load a blob from a distant file. </p>
  
  <pre><code>var r = new XMLHttpRequest();
  r.onload = function() { // Triggered only when all video is downloaded
      video.prop("src", URL.createObjectURL(r.response));
  };
  
  r.open("GET", "http://myserver/video.mp4");
  r.responseType = "blob";
  r.send();
  </code></pre>
  
  <p>As the application is for video stream, this method is not usable (unless we want the user to wait X minutes to download the whole file, which is not streaming at all).</p>
  
  <p>Is there any way to combine blob with progressive download ?</p>