Yes, there is problem with Windows. For some reason it's not using ffmpeg.dll that came with build. I tried installing FFmpeg manually, but after that I get same error as described here Error: spawn UNKNOWN. No wonder that some people call windows "Windblows" or "Shitblows" On linux you need to have installed ffmpeg but most Linux distributions came preinstalled with it and on macOS you can use brew to install it. If someone can try on Windows 7/8 with ffmpeg installed and give results it could be useful. Nex two weeks I'm busy with mu studies, but after that I will investigate more on this and fix this error on Windows.