Why doesn’t the “Video Embed Code” button work?

Screenshot: https://www.dropbox.com/s/mpppb48t3mz520z/Embed%20code.png

I’m going to a php file when I examine the button’s classes. The code is:

                        if ($  enable_embed == 'on') { ?>                         <script src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/1.6.0/clipboard.min.js"></script>                         <script>                             jQuery(document).ready(function($  ) {                                 var embed_code = '<iframe width="854" height="480" src="<?php echo $  embed_link; ?>" frameborder="0" allowfullscreen></iframe>'                                 $  ("#embed_code").val(embed_code);                             });                             new Clipboard('.copy-embed-code');