html:视频示例：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
*{
border:0;
padding:0;
margin:0;
box-sizing: border-box;
}
#v1,#v2{
width: 50%;
}
</style>
</head>
<body>
<video id="v1" src="../img/c.mp4" autoplay controls="controls">视频三</video>
<br>
<video id="v2" src="../img/d.mp4" autoplay controls="controls">视频四</video>
</body>
</html>结果如下图：
