You don't need to understand French to appreciate the importance of what these young people are doing as they pray the rosary in atonement for the profanation of the Catholic cathedral. Pay attention to the difference in the faces -- the masses of mostly elderly people there to celebrate the Protestant revolt vs. the faithful young people.
They were few in number, but so were the apostles, so were those who remained faithful in England after Henry VIII usurped the papal authority to make himself head of the Church in England.