Андрей Чернышев

$("form").on("submit", function(){
// code there
})

$("body").on("mouseover", "video", function(){
  this.play();
});
$("body").on("mouseleave", "video", function(){
  this.stop();
})

img {
  background-size: cover
}

<video autoplay="autoplay" loop="loop" width="2560" height="1440" poster="video/01.png" class="back-img">
        <source src="video/01.webm" type="video/webm; codecs=&quot;vp8, vorbis&quot;">
        <source src="video/01.mp4" type=" video/mp4; codecs=&quot;theora, vorbis&quot;">
        <source src="video/01.ogv" type="video/ogg; codecs=&quot;theora, vorbis&quot;">
        <source src="video/01.mp4" type=" video/mp4; codecs=&quot;avc1.42E01E, mp4a.40.2, vorbis&quot;">
      </video>