<div id="video_div" style="text-align:center;">
<button onclick="playPause()">播放/暂停</button>
<button onclick="toBig()">大</button>
<button onclick="toNormal()">中</button>
<button onclick="toSmall()">小</button>

<video id="myVideo" width="500" height="250" style="margin-top:15px;">
<source src="demo.mp4" type="video/mp4" />
<source src="demo.ogg" type="video/ogg" />
您的浏览器不支持此HTML5 视频标签。
</video>
</div>

<script type="text/javascript">
var myVideo=document.getElementById("myVideo");
function playPause()
{
if (myVideo.paused)
myVideo.play();
else
myVideo.pause();
}
function toBig()
{
myVideo.width=560;
}
function toNormal()
{
myVideo.width=420;
}
function toSmall()
{
myVideo.width=320;
}
</script>