Screen recording with audio is quite difficult in FreeBSD.
One solution is to use virtual_oss with sox and the same time to record Desktop using ffmpeg
At first need to install packages sox, libsoxr, virtual_oss, yad, xterm and ffmpeg
Then virtual_oss must be loaded and then Desktop recording with audio is possible.
Read also: https://puolanka.info/goto/desktop-audio-recorder-for-freebsd/