function changeImage(img, name) {
    document.getElementById(img).src = name;
}

function changeVideoImage(id, img, arr, i) {
	//pozice v nazvu souboru je 5, a tu nahrazujeme
	document.getElementById(id).src = img + arr[i]+'/';

	if (i == (arr.length-1)) {
		i = -1
	}
	
	var f = function() {changeVideoImage(id, img, arr, (i+1)); };
	to = setTimeout(f, 600);
}

function setDefaultVideoImage(id, img) {
	document.getElementById(id).src = img;
	clearInterval(to);
}