Unfortunately, latest FFMPEG versions stopped supporting Windows XP and Vista. If you want to make it work, you need to download earlier versions of FFMPEG. Please note, that the following source is not the official build and you download it at your own risk from third-party website.
1. Use following link to download:
FFmpeg.exe
2. Once you downloaded. Open Settings in the extension and click Browse. You need to select FFmpeg.exe that you just downloaded.
COPYRIGHT and LICENSE NOTICE