Anode and Cathode terminal of LCD is not connected in diagram shown. Probably as I searched on internet it must connected . Without this correction practical not work which may lead learners to wrong direction.Please correct it if I am write.
Arduino Arduino-with-LCD 04-05 min 40-50 sec
Please watch the video once again for more clarifications.
2:41 to 2.47 - It says:Pin 15 is the Anode of the backlight LCD.
Pin 16 is the Cathode of the backlight LCD.
5:12 - 5:24 - In the video, the connections are shown for Pin15 and Pin 16 (Anode and Cathode).