fix(LargeVideoManager): enable video problems filter on VideoContainer

Only the VideoContainer is interested in showing the video problems
filter which is meant to be displayed when ICE is disconnected.

modules/UI/shared_video/SharedVideo.js

         this.player = player;
     }
 
-    get $video () {
-        return this.$iframe;
-    }
-
     show () {
         let self = this;
         return new Promise(resolve => {

modules/UI/videolayout/LargeVideoManager.js

      * @param enable <tt>true</tt> to enable, <tt>false</tt> to disable
      */
     enableVideoProblemFilter (enable) {
-        let container = this.getContainer(this.state);
-        container.$video.toggleClass("videoProblemFilter", enable);
+        this.videoContainer.enableVideoProblemFilter(enable);
     }
 
     /**

modules/UI/videolayout/VideoContainer.js

         this.$video[0].onplay = onPlay;
     }
 
+    /**
+     * Enables a filter on the video which indicates that there are some
+     * problems with the media connection.
+     *
+     * @param {boolean} enable <tt>true</tt> if the filter is to be enabled or
+     * <tt>false</tt> otherwise.
+     */
+    enableVideoProblemFilter (enable) {
+        this.$video.toggleClass("videoProblemFilter", enable);
+    }
+
     /**
      * Get size of video element.
      * @returns {{width, height}}