Почему в chrome video.duration равен для некоторых видео NAN?

let showVideoTime = function () {
		let videoPageGallery = document.querySelectorAll('.video-page .video-page__item video');

		for (let i = 0; i < videoPageGallery.length; i++){
			videoPageGallery[i].addEventListener('loadedmetadata', (event) => {
				var mind = videoPageGallery[i].duration % (60 * 60);
				var minutes = Math.floor(mind / 60);

				var secd = mind % 60;
				var seconds = Math.ceil(secd);
				$(videoPageGallery[i]).parent().append('<span class="video-time">'+minutes+': '+seconds+'</span>');

			});
		}
	};
	showVideoTime();