I want to make a standalone application which can capture the screen run-time and display it on an external monitor.
I know simply duplicating the monitor works but I am interested in making an app for it.

I went through various forum questions for a solution and was inclined on doing it the DirectX way.
But turns out that DirectX way can only capture the screen of an app running through d3d.
It is not possible to create a standalone screencapturer using DirectX.

Correct me if I am wrong. I made this conclusion based on the question asked here: http://www.gamedev.net/topic/668163-full-working-example-to-capture-screen-using-directx/

It was suggested to do so using DXGI approach in the same thread.

Please help me out here.

I mention it again that I want to create a standalone screenrecording application which casts the content running on the main desktop onto an external monitor.

I am new to DirectX programming so I don't know about the intricacies involved.
Any amount of advice on creating the best (fastest) standalone screen capture application is appreciated.

I also refered to this blog http://blogs.msdn.com/b/dsui_team/archive/2013/03/25/ways-to-capture-the-screen.aspx

Here it was said that the GDI and D3D way can be used for a single screencapture.

Can somebody please explain why and how?

I am new to DirectX as I mentioned before and am not able to figure out the right direction in which I should go to get my job done.