js点击按钮实现带遮罩层的弹出视频效果

<div class="main">
  <a href="javascript:;" class="video" id="video"></a>
</div>

 <div class="video-btn" id="video-btn">
   <div class="video-area" id="video-area"></div>
   <a class="video-shut" id="video-shut">x</a>
 </div>
 <div id="shadow"></div>

.video-btn{
      position: absolute;
      width:600px;
      height: 300px;
      background:black;
      :50%;
      left: 50%;
      margin-: -150px;
      margin-left:-300px;
      display: none;
      z-index: 101;
    }
 .video-area{
      float:left;
      width:500px;
      height: 300px;
      background:red;
    }
.video-shut{
      height:100px;
      width:100px;
      font-size:40px;
      color:pink;
      float:left;
      text-align: center;
      /line-height: 50px;/
      background: yellow;
      display: block;
      padding-:30px;
    }

 #shadow{
      position: absolute;
      opacity: 0.5;
      filter:alpha(opacity=50);
      bottom:0;
      left: 0;
      right: 0;
      : 0;
      background:black;
      z-index: 100;
      display: none;
    }

<script>
  var obtn=document.getElementById('video');
  var ovideo=document.getElementById('video-btn');
  var oatn=document.getElementById('video-area');
  var oshut=document.getElementById('video-shut');
  var oshadow=document.getElementById('shadow');
  obtn.onclick=function () {
    ovideo.style.display='block';
    oshadow.style.display='block';
    oatn.innerHTML='<embed src="http://.tudou./v/Bs_lZPxcoRs/&rpid=818231113&autoPlay=true&resourceId=818231113_04_05_99/v.swf" allowFullScreen="true" quality="high" width="500" height="300" align="middle" allowScriptAess="always" flashvars ="isAutoPlay=true" type="application/x-shockwave-flash"></embed>';
  }
  oshut.onclick= function () {
    ovideo.style.display='none';
    oshadow.style.display='none';
  }
</script>