As a British person, I can safely say it is not them and they actually bear no resemblance to William and Harry other than hair colour.
"Do not pity the dead, Harry. Pity the living and above all, those who live without love."

Prince William, sad story, was played by Matthew Turpin who played the same role in another movie. But, on March 31, 2008, age 24, he died in Oxford of Sudden Arrhythmic (heart) Death Syndrome (SADS).
Sorry to hear this, sad story indeed

Actually, Prince Charles was played by Peter Hugo,
who has played exactly that same role in 6 other films and/or TV performances.
Prince Henry was played by Chris Castleno other details about him.
Prince William, sad story, was played by Matthew Turpin who played the same role in another movie. But, on March 31, 2008, age 24, he died in Oxford of Sudden Arrhythmic (heart) Death Syndrome (SADS).

Ha! You really thought they looked like them? I am not from England and thought they looked nothing liked them. Just the same hair color.

Considering they looked nothing like the real Prince William and Harry, no it was not really them. The credits give their real name.

Probably not even actors (in the common sense), just look-a-likes/impersonators.
Kind of like how Posh & Becks have impersonators who look pretty much exactly like them and get paid lots of money to turn up to parties and pretend to be them

No, they were just actors.