<input type="button" value="||" button id='play-pause-button'  class='play' title='play'
            onclick='togglePlayPause();'/>

document.addEventListener("DOMContentLoaded", function() { initialiseMediaPlayer(); }, false);

var mediaPlayer;

function initialiseMediaPlayer() {
   mediaPlayer = document.getElementById('media-video');
   mediaPlayer.controls = false;
}

function togglePlayPause() {
   var btn = document.getElementById('play-pause-button');
   if (mediaPlayer.paused || mediaPlayer.ended) {
      btn.title = 'pause';
      btn.innerHTML = 'pause';
      btn.className = 'pause';
      mediaPlayer.play();
   }
   else {
      btn.title = 'play';
      btn.innerHTML = 'play';
      btn.className = 'play';
      mediaPlayer.pause();
   }
}