Linking Slide to the URL

Hi,
As of now it is not possible to link button to an external url.

You could do something like this as you proposed : link to an existing page of your website and open a pop up window with your video inside.

To do that, you need
1) The linked page ID (easy to find in the url when editing the page in admin)
2) the External page URL

Copy and paste the code below in your functions.php

add_action( 'wp_head', 'my_popup_opening' );
function my_popup_opening(){
	global $wp_query;
    $id = $wp_query->get_queried_object_id();
//we only add this script if we display the specific page
    if (is_page() && YOURPAGEID == $id) {
    	?>
    		<script type='text/javascript'>
    			window.open("YOUREXTERNALURL", '_blank');
			</script>
    	<?php
    }
}