Anne was curtseying to The Queen, who was just out of the shot, not Camilla.
It has been confirmed many times before the court order of precedence is simply a protocol for royal events in terms of who sits where, who enters when and in what order, etc. They no longer curtesy or bow to one another based on their respective rank at court as they are all Royal Highnesses with the rank of Prince/Princess.
They do curtsey and bow to The Queen and Prince Philip at court.
It has been confirmed many times before the court order of precedence is simply a protocol for royal events in terms of who sits where, who enters when and in what order, etc. They no longer curtesy or bow to one another based on their respective rank at court as they are all Royal Highnesses with the rank of Prince/Princess.
They do curtsey and bow to The Queen and Prince Philip at court.