WordPress at a glance
filter is not described

get_header_video_url filter-hook . WP 4.7.3

Filters the header video URL.

Usage

add_filter( 'get_header_video_url', 'filter_function_name_9447' );
function filter_function_name_9447( $url ){
	// filter...

	return $url;
}
$url(string)
Header video URL, if available.

Where the hook is called

get_header_video_url()
wp-includes/theme.php 1353
$url = apply_filters( 'get_header_video_url', $url );

Where the hook is used (in WP core)

Does not used.