var arrlen = 2;
var urls = new Array(arrlen);
var heights = new Array(arrlen);
var widths = new Array(arrlen);

urls[0] = '<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/xM8A0cL6JEU"> </param> <embed src="http://www.youtube.com/v/xM8A0cL6JEU" type="application/x-shockwave-flash" width="600" height="350"> </embed> </object>';

urls[1] = '<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/gHAaK0jipIY"> </param> <embed src="http://www.youtube.com/v/gHAaK0jipIY" type="application/x-shockwave-flash" width="425" height="350"> </embed> </object>';

heights[0] = '350';
heights[1] = '350';
widths[0] = '450';
widths[1] = '450';

function openWindow(num)
{
    w=window.open('about:blank','mywindow','height=' + heights[num] + ', width=' + widths[num]);
        w.document.write(urls[num]);
}