In a sun-dappled video released September 9, Prince William and Princess Kate Middleton cuddled and frolicked with their three kids, Prince George, 11, Princess Charlotte, 9, and 6-year-old Prince Louis, in the countryside near their Norfolk, England, home and even engaged in some very non-royal PDA.

The Princess of Wales, seen walking alone in golden light as a dreamy soundtrack played, narrated the clip, meant to announce that she has completed chemotherapy for her undisclosed cancer.

As the three-minute mini-film concluded, watching a butterfly from her palm, Kate extended her thoughts to others facing cancer.

“I remain with you, side by side, hand in hand,” the 42-year-old said. “Out of darkness can come light, so let that light shine bright.”

It was an unprecedented move for the future king and queen, who have been fiercely private since announcing Kate’s diagnosis in March. But a source exclusively tells Life & Style, the intimate video is a sign of how her illness has changed Kate and how she sees her role moving forward.

“This has been a life-altering experience that’s not only brought her face-to-face with her own mortality, but it’s given her a new sense of spirituality, and taught her to appreciate the smaller things more, like nature, her children’s laughter, quiet moments with William,” says the insider. “It could have turned out so very differently. But Kate’s counting her blessings and appreciating every day with a little more clarity.”

Filmmaker Will Warr shot the video in August, while the royal family was on their summer holiday. Calling it an “honor” to make, he added, “This one was particularly poignant.”

That was Kate’s intention, says the insider. In addition to sharing her health update, the princess, always mindful of the need to modernize the monarchy, had a clear vision for the shoot.

Prince George of Wales, Prince William, Prince of Wales, Prince Louis of Wales, Princess Charlotte of Wales and Catherine, Princess of Wales
Chris Jackson/Getty Images

“Kate wanted her message to be simple yet cinematic in scale, and show her and her family having fun, playing games, enjoying a picnic and embracing,” says the insider. “Making the video was very much Kate’s idea, and she was in control, but also wanted it to come across as natural and without too much direction.”

Though some royal watchers were shocked by the clip, likening it to advertising, the Windsors have always had to prove their worth to their subjects. In fact, the insider says Kate referenced her late grandmother-in-law, Queen Elizabeth II, when storyboarding the film.

“It recalls the home movies of Prince Philip and the late Queen when they were young,” notes the source — minus the beach-blanket kissing, of course!

Interestingly, no one from William’s side of the family — including his father, King Charles III, who’s also battling cancer — appears in the video, which includes a lively scene of the young family playing a card game with Kate’s parents, Carole and Michael Middleton.

“This was Kate and William’s story,” says the insider. “It wouldn’t have been appropriate to include King Charles.”

While Kate said that the next stage of her cancer recovery has just begun, the popular royal did promise she will return to some duties as long as she feels well. The crowds have missed her, but the source says the princess has missed them too.

“One of the joys she’s missed during treatment was meeting people from all walks of life,” says the insider. “Getting to talk to them and sharing their lives.”