if( ! function_exists( 'videotube_filter_wp_video_extensions' ) ){
    /**
     * Filter default video extensions
     * @param  array $exts
     * @return array
     */
    function videotube_filter_wp_video_extensions( $exts ){

        $exts[] = 'mov';

        return $exts;
    }
    add_filter( 'wp_video_extensions', 'videotube_filter_wp_video_extensions',10, 1 );
}