Generally speaking, the options you're trying to set are not direct attributes of the constructor argument, but are children of the playerVars
attribute, like this:
<html>
<head>
</head>
<body>
<div id="myytplayer"></div>
<script>
var tag = document.createElement('script');
tag.src = "https://www.youtube.com/iframe_api";
var firstScriptTag = document.getElementsByTagName('script')[0];
firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);
var ytplayer;
window.onYouTubePlayerAPIReady = function() {
ytplayer = new YT.Player('myytplayer', {
height: 600,
width: 800,
playerVars: {
origin: 'http://designdeploy.co.uk',
modestbranding: 1,
controls: 0,
start: 403,
fs: 0,
showinfo: 0
},
videoId: '6KRJr7k6xns'
});
}
</script>
</body>
</html>
Here's a fiddle to demonstrate.