不使用videojs rtmp流的前贴片广告

Question

当我在videojs中放入rtmp流时，前贴片广告无效。 rtmp视频直接开始播放，并且不播放前贴片广告。但预推广告正在使用VOD

<video id="video"
     class="video-js vjs-default-skin"
     height="300"
     width="600" poster="http://jollyhoo.com/wp-content/uploads/2013/03/Priyanka-Chopra-Vogue-Magazine-March-2013-2.jpg" data-setup='{}'
     controls>
<p>
  Your browser doesn't support video. Please <a href="http://browsehappy.com/">upgrade your browser</a> to see the example.
</p>
<source src="rtmp://cp67126.edgefcs.net/ondemand/&mp4:mediapm/ovp/content/test/video/spacealonehd_sounas_640_300.mp4" type='rtmp/mp4'>

 </video>

 <script src="../video-js/video.js"></script>
 <script src="lib/videojs.ads.js"></script>
 <script src="src/videojs-preroll.js"></script>
    <script src="../videojs-logobrand-master/src/videojs.logobrand.js">     </script>
 <script>
// fire up the plugin
videojs('video',{plugins:{ads:{},preroll:{src:"http://static.bouncingminds.com/ads/5secs/baileys_5sec.mp4",href:"http://videojs.com"}}});
 </script>