I used a DirectX8 to DirectX9 converter that fixed the choppy videos and gameplay. Just put all the files in the installation folder. Copy and paste the following url to download it. I can't post hyperlinks on the forums.
enbdev.com/download_convertor_dx8todx9.htm

I then used the regular widescreen fix. So in my hitman2.ini I have:

Resolution 1920x1080
Window 1
StartUpperPos 0,0

I hope this is helpful for anyone new (as I am) coming here with issues playing the game.

Can we get this post stickied?

I concur.

GOG forums always useful. Thanks for the info.

Window 1? Doesn't this mean that the game will then be run in windowed mode? Is that the only way to get widescreen resolutions in this game? I don't want to run any game in windowed mode.

Because of the load on the computer? You can turn off the desktop in that case.

I had several issues... but think I found a working solution reading both Steam and GOG forums

Issues I had:
When first installed the "logo" videos and first "cut scene" didn't play - no sound no video, just a white box on the screen... if I hit ESC enough times and waited I eventually got the game menu, but when I would start a new game the screen would go black and although there was "music" playing it never showed anything or did anything...

The suggested fix under "support" for the game is to change the 3d graphics driver from D3D to OpenGL

When I made this change to the .ini file for the game, the opening videos and cut scene worked fine. In fact the first "tutorial" portion of the game rendered great and everything seemed to be working... but when I got to the first mission, the main character and most of the NPC characters rendered simply as black silhouettes.

Switching the 3d rendering back to D3D and escaping past the opening stuff, when I entered the 1st mission the character and NPCs rendered correctly - but the character himself seemed to move in slow motion..

It turns out this is because the application is not limiting the frame rate when rendering using D3D - but does when using OpenGL... if you use a 3rd party software to limit your frame rate to 60fps, then the D3D rendering will not be slow - which makes the videos and the game play work.

There are probably multiple Free options for doing this... but I used Bandicam as it seemed more "legit" and isn't tied to specific HW / graphics cards... Under the game capture menus simply tell it to limit the FPS and uncheck the "only when recording" option.

Having Bandicam running limiting the FPS for gaming - when I run the game everything seems to work fine - though I have not played all the way through the game as of yet.

Another note on some of the configurations mentioned here...

Setting the resolution and running in a window with these configurations:
Resolution 1920x1080
Window 1
StartUpperPos 0,0

works fine if the display you are running on is 1920x1080... This works because the windows refresh rate will be driven such that the frame rate works for the D3D rendering.

On my 4096x2160 screen however, it places a window in the top right quarter of my screen and plays the game there... if I set the window size to 4096x2160, then the game screen appears "full screen" as it matches my screen resolution - however the in game text is essentially too small to read...

My suggestion is to use a program like Bandicam to limit the framerate when you play the game to 60fps - then the configuration file as installed by GOG will work fine... you can use the "config" executable to set the resolution - though it doesn't have an option for 1920x1080 and setting it that high using full screen will fail.

Thanks, it worked for me, now the cinematics are played at the beginning.

This solved it for me. Thanks.

Thank you, kind stranger.