I checked and seems to be just Microphone (or other audio) input w/ QuickTime when recording sceengrab videos or recording just audio.
This is correct. And if you use a headset it won't pick up the general system sounds. Used it for an IEP call last week and found out afterwards the only audio it picked up was my own. Pretty frustrating.
yah, I just recently made the purchase for BlackHole because I couldn't get the system sounds otherwise. Great little project!