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, espeak-ng, wavpack and ffmpeg
Then virtual_oss must be loaded and then Desktop recording with audio is possible. If you have the wrong device (/dev/dspX) loaded for virtual_oss, recording does not work, so you need set the right device and reboot the computer.
When you have the right device loaded for virtual_oss, the test voice sounds like mickey mouse speaks.
Read also: https://puolanka.org/goto/desktop-audio-recorder-for-freebsd/
A version which does not use sox