DXEngine supports Windows 8.1 and it should work well there (I have tested it on many computers and it worked well; also my customers did not report that there would be any problems).
It would really help if you could you provide some additional information about the exception - inner exceptions and stack trace. It would also probably help if you could provide some additional context - how you create DXViewportView and what you show there.
I do not know in what format you get the video images - if you get a WPF BitmapSource or WinForms Bitmap, then DXEngine would not help you.
But if you get the video images as DirectX Texture2D, then it might be possible to use then with DXEngine - this way the images would not be copied from graphics card to main memory and back.
But there might be a problem if the DirectX Texture2D is not created by DirectX 11 - if it is created with DirectX 9, then DXEngine cannot use it. Theoretically the DirectX 9 texture can be shared between DirectX 9 and DirectX 11, though this was not testes yet (I only share a texture created in DirectX 11 with DirectX 9 - used by WPF).
Currently you could overlay any WPF content on top of DXEngine content when the DXViewportView is using DirectXImage as PresentationType (this mode sends the rendered DirectX 11 scene to WPF composition engine with creating a shared DirectX 9 texture). This can be used to show subtitles or any other 2D content.
If you would like to use DirectXOverlay (slightly faster because it uses SwapChain), you cannot show anything on top of DXViewportView. But I plan to add support for sprites and the it will be possible to add 2D images on top of the 3D scene.
This might be too technical so here is a quick summary:
DXEngine would help a Video player when it would be possible to share the texture created with Video decoder and DXEngine so that the texture would stay on the GPU. It is hard to say if this is possible. If you want to try this, please first read the documentation about the available formats. If this looks promising I can help you with that but I would need you to create a simple player application so that I could get the created texture. Then I would try to add code that would use that texture in DXEngine.
This might work, but is a more complicated way to solve that. It would be easier to add video to WPF with using D3DImage control - search for "D3DImage video player" and you might get a more simple solution.
I see now - you got a dialog that you are using an "unlicensed version of Ab3d.PowerToys library". This means that the evaluation version of Ab3d.PowerToys was not started on the computer.
Have you installed the evaluation version on this computer?
Instead of the "unlicensed version" dialog you should get a dialog telling that you which day of evaluation you are using.
Hm, this is strange.
The evaluation process should be automatically started when you installed the "AB4D Products Installer (Trial).exe".
I will contact you with email with some additional information.
We have found out that there was a problem in the installer when user selected to create Shortcuts only for him and not for all users on the computer (which is the default).
In this case installer shows "Error installing products. Error code: -1", but the files were still installed on the disk. But because of an error the evaluation was not started and this prevented using the libraries.
I will fix that and improve the messages in the error dialogs.