Custom fields metabox

<style>
#adjuntos .line {
    margin: 4px 0;
    padding: 0;
    border: 0;
    margin: 0;
}
#adjuntos .line td {
    padding: 4px;
    margin: 4px 0;
    border-top: 1px solid #dfdfdf;
}

#adjuntos {
    width: 100%;
    border: 0;
    padding: 0;
}
</style>


<table id="template" style="display: none">
    <tr class="line">
        <td width="40%">
        <label><?php _e('Título del video:'); ?></label>
        <p>
          <input type="text" name="video_title[]" id="video_title[]" value="" class="title regular-text" style="width: 98%" />
          <span class="description"><?php _e('Nombre del video.'); ?></span>
        </p>
        </td>

        <td width="50%">
        <label><?php _e('URL del video:'); ?></label>
        <p>
          <input type="text" name="video_url[]" id="video_url[]" value="" class="url regular-text" style="width: 98%" />
          <span class="description"><?php _e('URL del video de Youtube.'); ?></span>
        </p>
        </td>

        <td width="10%" class="commands">
            <a rel="delete" class="button">-</a> <a rel="add" class="button">+</a>
        </td>

    </tr>
</table>

<table id="adjuntos">

</table>


<script>
(function($)
{
    lines = 0;

    function items_init()
    {
        <?php $videos = get_post_meta($post->ID, 'videos', true) ?>

        <?php if ( empty($videos) ) : ?>
        items_add();
        <?php else: ?>

        <?php
        // get serialized data
        $videos = unserialize($videos);

        // Show stored records
        foreach ($videos as $video) : ?>
        items_add({
            title: '<?php echo $video['title'] ?>',
            url:   '<?php echo $video['url'] ?>'
        });
        <?php endforeach ?>
        <?php endif ?>

        // Delete the "-" button in first row
        $('#adjuntos tr:first-child .commands a[rel="delete"]').remove();
    }

    function items_add()
    {
        obj = $('#template tr:first-child').clone().appendTo('#adjuntos');
        lines++;

        if (arguments.length > 0) {
            options = arguments[0];

            $('.title', obj).val( options.title );
            $('.url',   obj).val( options.url );
        }
    }

    $('#adjuntos').delegate('.commands a', 'click', function()
    {
        var action = $(this).attr('rel');
        var confirm_delete = true;

        // Add action
        if ('add' == action) {
            items_add();
        }

        // Delete action
        if ('delete' == action) {
            // La TR en la tabla
            var oTr = $(this).parent().parent();
            var video_name = $('.title', oTr).val();
            var video_url  = $('.url', oTr).val();

            if (video_name != '' || video_url != '') {
                if ( !confirm('Are you sure you want to delete ' + video_name + '?') ) {
                    confirm_delete = false;
                }
            }

            if (confirm_delete) {
                oTr.remove();
                lines--;
            }
        }
    });

    $(document).ready(function()
    {
        items_init();
    });

})(jQuery);

</script>