for swf e.g. a really flexible rezize is THIS
jQuery(document).ready(function($){
$('a[href$=".swf"]:not(.nofancybox)').addClass('fancybox-swf'); //search for links with .swf and add a class
$('a.fancybox-swf, area.fancybox-swf').each(function(){ //in the id attribute (you can take what you want) is the size given like: "800, 600"
var $a = $(this);
var swfID = $a.attr('id');
var data = swfID.split(", ");
var swfWidth = parseInt(data[0]); //get the size
var swfHeight = parseInt(data[1]);
$a.fancybox({ //do the fancybox call
'type' : 'swf',
'width' : swfWidth,
'height' : swfHeight
});
});
});