x
 
<!DOCTYPE html> 
<html> 
<body> 
<p>本例演示如何将 "onprogress" 事件分配给 video 元素。</p>
<video controls onprogress="myFunction()">
  <source src="/i/photo/shanghai.mp4" type="video/mp4">
  Your browser does not support HTML5 video.
</video>
<script>
function myFunction() {
  alert("Downloading video");
}
</script>
</body> 
</html>