Add File Size Column to Media Library

<?php
if ( ! function_exists( 'scseed_add_filesize_column' ) ) {
    function scseed_add_filesize_column( $columns ) {
        $columns['scseed_filesize'] = __( 'File Size', 'scseed' );
        return $columns;
    }
}
if ( ! function_exists( 'scseed_show_filesize_column' ) ) {
    function scseed_show_filesize_column( $column, $post_id ) {
        if ( 'scseed_filesize' !== $column ) {
            return;
        }
        $file = get_attached_file( $post_id );
        if ( $file && file_exists( $file ) ) {
            echo esc_html( size_format( filesize( $file ) ) );
        } else {
            echo '&mdash;';
        }
    }
}
add_filter( 'manage_media_columns', 'scseed_add_filesize_column' );
add_action( 'manage_media_custom_column', 'scseed_show_filesize_column', 10, 2 );