Eadweard,
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<select name="city" id="myselect">
<option value="1">Серия 1</option>
<option value="2">Серия 2</option>
<option value="3">Серия 3</option>
<option value="4">Серия 4</option>
</select>
<div id="mydiv">src="http://s5.lol.com/video/a3c86e0a3/" width="610" height="370"</div>
<script type="text/javascript">
var obj = {1 : 'http://sggghhgh', 2 : 'http://suiiuiuiui'}// и т.д.
document.getElementById("myselect").addEventListener("change", function(){
document.getElementById('mydiv').innerHTML = 'src="'+obj[this.value]+'" width="610" height="370"';
});
</script>
</body>
</html>