Adds comments for processing nextOnStage.

modules/FollowMe.js

     _onNextOnStage(id) {
         var clickId = null;
         var pin;
+        // if there is an id which is not pinned we schedule it for pin only the
+        // first time
         if(typeof id !== 'undefined' && !VideoLayout.isPinned(id)) {
             clickId = id;
             pin = true;
         }
+        // if there is no id, but we have a pinned one, let's unpin
         else if (typeof id == 'undefined' && VideoLayout.getPinnedId()) {
             clickId = VideoLayout.getPinnedId();
             pin = false;