Hi all! I had just completed the Mood Cue project earlier.
However, I felt like I more or less understood all the parts of the project except for one thing: I didnt understand why the capacitor was there?
From reading the manual, I get that the servo draws more current when it "starts" to move. So does it mean that the arduino would not be able to give enough power to "start" the servo to move at all if there was not a capacitor? However, that would sound a little strange to me as well because as long as the servo's voltage rating is within the output voltage range of the arduino, shouldnt the arduino be able to support the servo's power needs no matter what?
And furthermore, I am also completely lost as to why I need to connect a capacitor across the potentiometer 
Thanks! I am eventually going to study electrical engineering so I would love to be able to understand why I am adding certain components into the circuit rather than just simply using them because the manual told me to do so :)!