Here's public repository to check and build yourself. I will less buggy in future :
https://github.com/kalipsers/DuoPlayer

Thanks a lot for your recommendations.

There's a new version :

Hello, my first project here. I created software for playing estim videos with seperate audio file.
1. Load mp3 file

First Window.png

2. Load mp4 file, it should work with other video files too, tested only on mp4

Second Window.png

3. Choose mp3 file output device

Third Window.png

4 ...