It is recommended to always download the latest version of FFmpeg using FFmpeg Downloader. Older versions of FFmpeg can cause unexpected behaviour.
FFmpeg is an open-source cross-platform solution to record, convert and stream audio and video. It adds support for more output formats like H.264 for Video and Mp3, AAC etc. when capturing Only Audio.
FFmpeg is configured on the FFmpeg section in the Configure tab.
Due to its large size (approx. 30MB), it is not included in the downloads. If you already have FFmpeg on your system, you can just set the path to the folder containing it. If it is installed globally (available in PATH), you don't have to do anything. If you don't have FFmpeg or want to update, use the inbuilt FFmpeg Downloader. FFmpeg needs to be downloaded only once.
In cases where the FFmpeg Downloader fails, please download manually from https://ffmpeg.zeranoe.com/builds/ and set FFmpeg folder in Configure | FFmpeg.
If you don't want to use FFmpeg, you can switch to SharpAvi.