Update: I have switched PWM pins 10 and 11 with 7 and 8 and now all of the LEDs are flashing 
However, I get no sound output unless I touch the leeds of the LEDs. When I do, the sound is not as in the video and is very faint. Also, I seem to get no response from messing with the potentiometer knobs.
P.S.: I don't know how big of a deal it is, but for one of the capacitors I put a 0.22uF one instead of 0.1uF as it is listed in the diagram.
Cheers,
Calin