I don't speak Swedish at all (I mainly infer the meaning from some similarities to German) but if you watch the King's speech in the video, I think he mentions that he remembers his own coming of age ceremony and he gave a date for it which I didn't understand.
Here is Google translation of King's speech to CP Victoria
Dear Victoria,
it is now your special day.
We are gathered in the Hall to express our congratulations and also celebrate that now you have achieved the power, as the crown princess, assist me in my major acquisition by the Swedish head of state.
To my mind even in clear memory my allegiance to the Swedish Parliament, here in the Hall in January 1995. I am convinced that your myndighetsdag in the same way will be a milestone also in your life.
You still have several years ahead of study and training. This allows you to well prepare for your future tasks. You are also a link to the future of our country's history. As heir to the throne, you carry in Sweden and the royal family traditions.
It is with great pleasure that I here, to you as a daughter and Sweden's crown princess, expressing your mother's and my own deep trust. We know a lot of confidence for your future deeds and we will always, with your other family, to support and assist you in any way.
Today I have bestowed upon you Seraphim, as a sign of your new-found status and the responsibilities it entails. It is my belief that you in the future with honor and respect will carry this order.
Your mother and I wish you all happiness and success. May God protect you.