demo/bufferAll.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8"/>
  </head>
  <body>
    <video controls></video>
    <script>
      var video = document.querySelector('video');

      var assetURL = 'frag_bunny.mp4';
      // Need to be specific for Blink regarding codecs
      // ./mp4info frag_bunny.mp4 | grep Codec
      var mimeCodec = 'video/mp4; codecs="avc1.42E01E, mp4a.40.2"';

      if ('MediaSource' in window && MediaSource.isTypeSupported(mimeCodec)) {
        var mediaSource = new MediaSource;
        //console.log(mediaSource.readyState); // closed
        video.src = URL.createObjectURL(mediaSource);
        mediaSource.addEventListener('sourceopen', sourceOpen);
      } else {
        console.error('Unsupported MIME type or codec: ', mimeCodec);
      }

      function sourceOpen (_) {
        //console.log(this.readyState); // open
        var mediaSource = this;
        var sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
        fetchAB(assetURL, function (buf) {
          sourceBuffer.addEventListener('updateend', function (_) {
            mediaSource.endOfStream();
            video.play();
            //console.log(mediaSource.readyState); // ended
          });
          sourceBuffer.appendBuffer(buf);
        });
      };

      function fetchAB (url, cb) {
        console.log(url);
        var xhr = new XMLHttpRequest;
        xhr.open('get', url);
        xhr.responseType = 'arraybuffer';
        xhr.onload = function () {
          cb(xhr.response);
        };
        xhr.send();
      };
    </script>
  </body>
</html>