LONDON -- Public displays of affection on a royal video? My, how times have changed!

When the Princess of Wales announced that she had completed chemotherapy treatment in a soft-focus, Insta-ready video, she ventured into realms not previously inhabited by Britain's royal family, traditionally known for the stiff-upper-lip, "never complain, never explain" ethos of the late Queen Elizabeth II.

Here was the most popular royal, a public figure usually known simply as Kate, using the tools of social media to share the fact that for all her wealth and privilege, her life had been upended by cancer, just like millions of other people.

But it wasn't just what she said; it was how she said it. Unlike earlier updates on Kate's health, which sounded like factual news reports, this had an entirely different tone. The slickly produced mini-movie released Monday showed the princess hugging Prince William and their three young children and sharing intimate moments at home with her parents.

There's even a chaste kiss on her cheek.

"It is a real break,'' said George Gross, a royal historian at King's College London. "But I think people will look at it and won't necessarily realize that. I think they will think: This is just right; this is normal. That's what a family does."