Turn video into Blob object?

Question

I found this code in a tutorial that to turn videos into objects and be treated as if it were a url blob, with the first video with comes on the page the function works perfectly, but when I call another video through the Ajax the same does not reproduce, the only purpose of this code is to help protect the original path of videos to avoid direct access, which may be wrong?

function mascara()
{
    var ms = new MediaSource();

    var video = document.querySelector('source');
    video.src = window.URL.createObjectURL(ms);

    ms.addEventListener('sourceopen', function(e) {

      var sourceBuffer = ms.addSourceBuffer('video/mp4; codecs="avc1.42E01E, mp4a.40.2"');
      sourceBuffer.appendBuffer(oneVideoWebMChunk);

    }, false);
};