[LaputanMachine]

If you want to record sound generated by the computer itself only (not the microphone), you can use a tool like BlackHole [1].

BlackHole adds a loopback audio device which can be used with the default video capture tool (select the loopback device in the options menu after pressing shift-command-5).

To be able to play audio from the speakers while you're recording, you need to add a multi-output audio device in the macOS "Audio MIDI Setup" app. Switch to the multi-output device by option-clicking the audio icon in the top menu bar. Now both the speakers as well as the BlackHole audio device will receive audio.

[1]: https://github.com/ExistentialAudio/BlackHole

[oplav]

This is also really useful if you need to mute a Zoom call if you need to listen to something else (like an unrelated video). You can just temporarily set the Zoom audio output to the BlackHole device.