pauseVideo.js

// Sample HTML
//<video id="video1" controls>
//  <source src="/path/to/video.webm" type="video/webm">
//</video> 
// <div class="playButton"></div>
// realistically you would create custom play buttons so you can control from JS

var video = document.getElementById("video1");
var playButton = document.getElementsByClassName("playButton")[0];

video.pause() // will pause video
video.play() // will play video.

// you can wrap those methods in a event handler like a click on the play button div 

playButton.addEventListener("click", function(event){
  if (video.pause()) {
    video.play();
  } else {
    video.pause();
  }
})