rognarek,
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<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
.fullscreen-bg img{
width: 100%;
}
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<div class="fullscreen-bg">
<img id="im_but" class="fullscreen-bg__video" src="http://vcinema.pro/images/bg_glavnaya.png" style="position:absolute; z-index:1000; left:0; top:0;"/>
<video id="video_main" class="fullscreen-bg__video video-js vjs-default-skin" preload="none" width="100%" poster="http://vcinema.pro/images/FON_GLAV.jpg" data-setup="{}">
<source src="http://vcinema.pro/wp-content/uploads/2018/08/SOS_GLAVNAYA.mp4" type='video/mp4' />
<source src="http://vcinema.pro/wp-content/uploads/2018/08/SOS_GLAVNAYA.webm" type='video/webm' />
</video>
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<script>
document.addEventListener("DOMContentLoaded", function() {
var btn = document.getElementById("im_but");
var myVideo = document.getElementById("video_main");
btn.addEventListener("click", function() {
btn.style.display = "none";
myVideo.play()
});
myVideo.addEventListener("ended", function() {
//this.load();
myVideo.src = myVideo.currentSrc;
myVideo.pause();
btn.style.display = "block"
})
});
</script>
</body>
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