Some fun with asp.net mvc dynamic model binder

DynamicModelBinder.cs

    protected void Application_Start()
    {
        ModelBinders.Binders.DefaultBinder = new DynamicModelBinder(ModelBinders.Binders.DefaultBinder);
    }

    public class DynamicModel : DynamicObject
    {
        readonly NameValueCollection _attributes;

        public DynamicModel(NameValueCollection attributes)
        {
            _attributes = attributes;
        }

        public override bool TryGetMember(GetMemberBinder binder, out object result)
        {
            result = _attributes[binder.Name];
            return true;
        }
    }

    public class DynamicModelBinder : IModelBinder
    {
        readonly IModelBinder _defaultBinder;

        public DynamicModelBinder(IModelBinder defaultBinder)
        {
            _defaultBinder = defaultBinder;
        }

        public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
        {
            if (bindingContext.ModelType == typeof(object))
            {
                var form = controllerContext.HttpContext.Request.Form;
                var model = new DynamicModel(form);
                return model;
            }
            else
            {
                return _defaultBinder.BindModel(controllerContext, bindingContext);
            }
        }
    }

DynamicModel how to use the controller? Can not seem to understand.

Maybe I did not put it quite right. I can not figure out how to cast the object to DynamicModel MyModel? Thanks in advance for your help.