Just looked again at the video. He answered your question in the comments:
"I assume you are referring to the pushbuttons with the internal LED¡¯s in the yard ladder I showed in the first control panel video. Those came from and are an LP1-OA-1-A-G with the last letter indicating the LED color, in this case green. They are $2.12 for 10 or more but the price does continue to decrease with increasing volume. I just checked and they still have them."
