It was beautiful, especially to see children involved in deepening their faith. But Cardianl Arinze who is in charge I think of the Liturgy Norms perviously said there should not be anything at mass, in the Western Rite in Europe and America, that detracted from the Sacrifice and specifically mentioned dancing. The reason for this is that the reason for the Mass is the Sacrifice itself: But let Cardinal Arinze speak for himself:
Actually, reading the post, I cannot be sure if they had an actual Mass or if it was just a service for receiving ashes. The wording makes it sound like perhaps it wasn't really a Mass. Remember, non-Catholic reporters don't know the difference. Either way, I would hope if it was a Mass, that the performance was AFTER the Mass was concluded. Using a church for a performance should be fine...just not in the middle of a Mass...but after Mass, I don't see why not.