Screencast with ONLY Internal Audio

This can be really useful if you are for example, doing a screencast, and want to record internal audio, like a song playing in iTunes, or a video clip, but don't want to capture external noise, either because of lack of quiet (classroom) or just because even if it is quiet it will mean really poor audio quality.

Then read on.

1. Download and install the Soundflower

2. Now you can adjust Audio Setup

3. If you've upgraded to Sierra (or later), just click on the audio icon on the menu

4. From the drop down menu, choose Soundflower (2ch)

5. Now you can choose to record only internal audio

6. Open up your recording app, like QuickTime

7. Choose Soundflower (2ch) as your input instead of microphone

8. Now you can record away, and room noise will be unheard

Don't forget to switch it back to normal afterwards!