import flash.utils.getDefinitionByName;
import flash.utils.getQualifiedClassName;

/*var ClassRef: Class = getDefinitionByName(getQualifiedClassName(gameMc)) as Class;
var clone_mc: DisplayObject = new ClassRef();
this.addChild(clone_mc);*/

var ClassRef: Class = gameMc.constructor;
var clone_mc: MovieClip = new ClassRef();
addChild(clone_mc);

二选一