title: using typeof InstallTrigger !== 'undefined' for video play detection
body: <p>What I am trying to do is largely the same as <a href="https://stackoverflow.com/questions/5278262/click-the-poster-image-the-html5-video-plays">Click the poster image the HTML5 video plays?</a>. As you can see in the comments of the answer, it is noted that firefox (and other browsers) automatically play the video if you click on the poster anyway, while IE does not. To get around this issue, they say to use</p>
  
  <pre><code>typeof InstallTrigger !== 'undefined'
  </code></pre>
  
  <p>To determine whether or not to play the video. However, in the linked post, 
  <a href="https://stackoverflow.com/questions/9847580/how-to-detect-safari-chrome-ie-firefox-and-opera-browser/9851769#9851769">How to detect Safari, Chrome, IE, Firefox and Opera browser?</a>, there is heated discussion over browser detection being 'bad practice'. So, is there a way to force clicking on the poster to play the video regardless of the browser and without installtrigger. Beyond just playing the video, I noticed that for example Firefox has a play button centered in its video, and IE does not so I would like to display that button if it is not there.</p>
  
  <p>Code:
  HTML:</p>
  
  <pre><code>&lt;div class="glyphicon glyphicon-play big-play-button" ng-class='{inactive: play_btn_visible}' ng-click="play_video()"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>JS (note the all caps): </p>
  
  <pre><code> scope.play_btn_visible = SHOULD THERE BE A CENTRAL PLAY BUTTON?;
          scope.play_video = function() {
              if (WILL THE VIDEO NOT BE AUTO-PLAYED ALREADY?) {
                  elem[0].querySelector("video").play();
              }
          }
  </code></pre>