<video autoplay loop poster="http://wazenmiyabi.info/wp-content/themes/wazenmiyabi/movie/samplebgv.jpg" id="bgv">
  <source src="http://wazenmiyabi.info/wp-content/themes/wazenmiyabi/movie/samplebgv.webm" type="video/webm">
  <source src="http://wazenmiyabi.info/wp-content/themes/wazenmiyabi/movie/samplebgv.mp4" type="video/mp4">
</video>
<div id="bgvdot"></div>
<div id="wrap">
  <p>contents</p>
</div>

#bgv {
  position: fixed;
  right: 0;
  top: 0;
  min-width:100%;
  min-height:100%;
  width: auto;
  height: auto;
  z-index: -9999;
  background: url(http://wazenmiyabi.info/wp-content/themes/wazenmiyabi/movie/samplebgv.jpg) no-repeat;
  background-size: cover;
}
#bgv source{
  width:100%;
  height:auto;
}
#bgvdot{
  position:fixed;
  top:0;
  left:0;
  width:100%;
  height:100%;
  background:url(http://wazenmiyabi.info/wp-content/themes/wazenmiyabi/images/share/wrap1.png);
  background-size:auto;
  z-index:-9998;
}
#wrap p{
  background:rgba(255,255,255,.7);
  border:1px solid white;
  padding:20px;
  width:300px;
  text-align:center;
  font-size:200%;
  margin:50px auto;
}