Filter the automatic featured images from videos content to pull from a postmeta value

automatic_feature_image_filter.php

<?php

function filter_featured_images_from_videos( $content ) {
	global $post;

	$content .= get_post_meta( $post->ID, '_video_url', true );
	return $content;

}
add_filter( 'wds_featured_images_from_video_filter_content', 'filter_featured_images_from_videos' );