Why are these people called the "All blacks", when they are almost all white?
Is it some weird form of racism? Some people are in fact uncomfortable with the name but it's unlikely ever to be changed. It is of course the New Zealand rugby team, current world champions. "Black" refers to the color of their customary uniforms. Rugby tends to be a middle to upper class game, though in NZ it is the national sport. American football developed from Rugby origins. The players in the picture are performing a Maori Haka. Maori culture is treated with respect in NZ and the Haka has been widely adopted. It is basically a war dance.
The 2015 trophy was presented to the winners by Prince Harry, who is himself a keen sportsman. The Royal presence at the game elevated the occasion and undoubtedly helped the Prince's already high esteem in British Commonwealth countries.
Story of the 2015 match here