Check metabox to add a body class, then include scripts if condition is met.

body_class_to_load_scripts_condition.php

/* IN YOUR TEMPLATE FILE ABOVE THE HEADER CALL */

	add_action( 'body_class', 'add_my_bodyclass'); 
	function add_my_bodyclass( $classes ) {

	global $post;
	$condition = get_post_meta( $post->ID, 'METABOX_ID', true );

	// Some condition to compare / check
  	if ( ! EMPTY( $conditon ) ) :
      	$classes[] = 'CUSTOM_CLASS'; 
  	endif;
		  $classes[] = ''; 

		return $classes; 
	} 


/* THEN IN THE ENQUE FUNCTION */

$classes = get_body_class(); // Check body classes must be included

 if ( in_array('CUSTOM_CLASS', $classes) ) :
        wp_enqueue_script( 'video', get_template_directory_uri() . '/assets/js/jquery.background-video.js', array( 'jquery' ), '1.0.0', true );
 endif;