How to display Text in Tabpane created in Product-Edit page in NopCommerce?

Question

I am creating my own plug-in in which i want to add tab to Product-Edit page and in that i want to display one list.

For that i have written following code in the HandleEvent:

 public void HandleEvent(AdminTabStripCreated eventMessage)
        {
            if (eventMessage.TabStripName == "product-edit")
            {
                var controller = new ProductVideoController();
                var html = controller.Configure();
                eventMessage.ItemFactory.Add().Text
("My List").ContentHtmlAttributes(html);
            }
        }

But, it gives me an error that object reference does not set to an instance of an object in var html = controller.Configure(); statement;

Can anyone has any idea?

All answers are accepted.

Thanks in anticipation.