Speaking to William - who is married to Catherine, Duchess of Cambridge - Harry said: "Which is insane because actually you know, I don't know whether your wife doesn't, my wife certainly goes, "Well why turn the lights off?"
William, who noted that he also wants his father to focus on his health, continued, "When he's there, he's brilliant, but we need him there as much as possible".
"I was very grateful for him to be able to do that".
William's desire to have Charles spend more time with his immediate family comes just months after The Daily Beast reported that William and his brother, Prince Harry, have a "strained" relationship with their father. This is the third time the public has seen William and Kate's newest addition since his arrival in April.
Louis will be joined by another cousin next year, as Kensington Palace recently announced that Prince Harry and Meghan Markle are expecting their first child.
We should clarify that Prince Charles didn't exactly accompany Meghan down the aisle in the role of her father-she made the fearless decision to begin her walk down the aisle of St George's Chapel at Windsor Castle alone. Charles met her halfway, whereupon he accompanied her to the altar.
In the documentary, Harry says of that moment, "You've got to say thank you".
Charles' wife, Camilla, Duchess of Cornwall, discussed Charles' role as a grandparent in the documentary, revealing that the royal is happy to get a little silly with his grandchildren.
"He reads Harry Potter and he can do all the different voices and I think children really appreciate that".
"He will get down on his knees and crawl about with them for hours, you know, making amusing noises and laughing, and my grandchildren adore him, absolutely adore him", the Duchess of Cornwall revealed in the documentary.