[Hauts]

import flash.external.ExternalInterface;
function resizeInHTML(width, height) {
	_global.__jsId = Math.random();
	if (!_root.__getJsId) {
		_root.__getJsId = function() {
			return _global.__jsId;
		};
		ExternalInterface.addCallback("__getJsId",_root, _root.__getJsId);
	}
	var callFunction = "function(needId,width,height){";
	callFunction += "var elements = document.getElementsByTagName('object');";
	callFunction += "for(var k = 0 ; k < elements.length; k ++){";
	callFunction += "var element = elements[k];";
	callFunction += "if(element.__getJsId != undefined){";
	callFunction += "if(needId == element.__getJsId()){";
	callFunction += "element.style.width = width;";
	callFunction += "element.style.height = height;";
	callFunction += "return;";
	callFunction += "};";
	callFunction += "}";
	callFunction += "}";
	callFunction += "}";
	ExternalInterface.call(callFunction,_global.__jsId,width,height);
}
 
// Test:
this.onMouseDown = function() {
	resizeInHTML(100 + Math.floor(Math.random() * 100) + "px",100 + Math.floor(Math.random() * 100) + "px");
};

Не ручаюсь, что будет хорошо работать во всех браузерах.

P.S. Тестировать не локально.