function replace_with( url, type ) {

	//get ref to element
	var large_img = document.getElementById('large_image');
	var video = document.getElementById('video');

	if( type == 'image' ) {

		large_img.style.display = 'inline';
		video.style.display = 'none';

		//get new source
		var new_src = large_img.src.replace( /^(.+\?src=\.\.\/)[^\&]+(\&.+)$/, '$1' + url + '$2' );
	
		//alert(new_src)
		large_img.src = new_src;
	
	} else {

		large_img.style.display = 'none';
		video.style.display = 'inline';
		
		var html = 
			'<object width="600" height="485">' +
			'<param name="movie" value="http://www.youtube.com/v/' + url + '&hl=en_GB&fs=1&"></param>' +
			'<param name="allowFullScreen" value="true"></param>' +
			'<param name="allowscriptaccess" value="always"></param>' +
			'<embed src="http://www.youtube.com/v/' + url + '&hl=en_GB&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="600" height="485"></embed>' +
			'</object>';
		
		video.innerHTML = html;
		
	}

}