seek lock

<script>
jQuery(document).ready(function($){
$('.unit_content').find('audio,video').each(function(){ 
    if(typeof this.player !== "undefined"){ 


      if(!$('#mark-complete').hasClass('tip')){return;} 

          var _player = this.player;

            old = _player.media.setCurrentTime; 
            _player.media.setCurrentTime = function(time) { 

                if(time <= this.currentTime){ 
                    old.apply(this,[time]); 
                }
            };

    }
  });
$(document).on('media_loaded','#mark-complete',function(){
  
  $('.unit_content').find('audio,video').each(function(){ 
    if(typeof this.player !== "undefined"){ 


      if(!$('#mark-complete').hasClass('tip')){return;} 

          var _player = this.player;

            old = _player.media.setCurrentTime; 
            _player.media.setCurrentTime = function(time) { 

                if(time <= this.currentTime){ 
                    old.apply(this,[time]); 
                }
            };

    }
  });  
});
});
</script>