JSFiddle - React, Tailwind, and code Playground

HTML

<video id="video" width="320" height="240" preload="auto"></video>

CSS

video{
    background:none;
}

JavaScript

var video = document.getElementById('video');
var source = document.createElement('source');

source.setAttribute('src', 'http://techslides.com/demos/sample-videos/small.mp4');

video.appendChild(source);
video.play();

setTimeout(function() {  
    video.pause();
    
   source.setAttribute('src', 'http://hwcdn.net/j9t9v3v5/cds/Foreman_H264.mp4'); 
    
    video.load();
    video.play();
}, 3000);