Hi there Cinettoa.
The ReSpeaker Mic Array v2.0 out-of-box demo is not about noise suppression, such as quieting an AC unit or fan. It is about AEC, or canceling nose that is being played by the mic array itself.
The reason you are not seeing any activity on line 5 is because line five is the audio output from the Mic Array.
In the video all of the music is from the Mic Array itself.
Hope this helps!