Se a pergunta se referir ao vídeo do YouTube no primeiro comentário, essa música é o Hogwarts School Song como descrito no primeiro livro Harry Potter e a Pedra Filosofal -
Capítulo 7: O chapéu de classificação:
'And now, before we go to bed, let us sing the school song!' cried Dumbledore...'everyone pick their favorite tune,' said Dumbledore, 'and off we go!' And the school bellowed:
Hogwarts, Hogwarts, Hoggy Warty
Hogwarts,
Teach us something please,
Whether we be old and bald
Or young with scabby knees,
Our heads could do with filling
With some interesting stuff,
For now they're bare and full of air,
Dead flies and bits of fluff,
So teach us things worth knowing,
Bring back what we've forgot,
Just do your best, we'll do the rest,
And learn until our brains all rot.
Everybody finished the song at different times. At last, only the Weasley twins were left singing along to a very slow funeral march