是否可以在JavaScript中保存MediaStream？

Question

基于this article，可以使用MediaStream方法捕获video元素的captureStream()：

var leftVideo = document.getElementById('leftVideo');
var rightVideo = document.getElementById('rightVideo');

leftVideo.onplay = function() {
  // Set the source of one <video> element to be a stream from another.
  var stream = leftVideo.captureStream();
  rightVideo.srcObject = stream;
};

但是，我想使用JavaScript将流保存到文件中。有可能吗？