Free download and install Soundflower to record audio on your Mac.
1. Go System Preferences -> Sound.
2. Click Input and choose Internal Microphone.
3. Clike Output and choose Multi-output Device.
4. When you prepare to record, open Filmage Screen, select an area, then choose System Audio(Soundflower(64ch)) in audio sources.
If you want to learn more about audio recorder, please click Here.
If you want to know how to create Aggregate Device and Multi-output Device, please click Here.