During his first deployment Prince Harry was taken care by Gurkha soldiers, the worst paid, he is of notoriety too, hence the MOD decided to make out of him a public relations marketing tool in form of a documentary video doing the walking round, showing his bunker, firing the machine gun, etc.
I think the documentary is great way to showcase what the United Kingdom has through a VIP. Much more people will watch a documentary with Harry rather than Joe.