Most people who will watch this documentary will be interested in what they reveal about their personal lives and couldn't care less about saving animals or whatever the charity is - it is just another charity with a royal so 'big deal' - sadly they don't register with most people which one it is they are representing on any particular occasion. There will be some mention of a whatever Willam says - about their private lives if anything - and what Kate wears and nothing much on the issue itself.
This isn't just William and Kate but all the royals - the charities themselves don't actually register or mean anything to the majority of people - it is seeing a royal or noting what the woman was wearing.