"That's a young girl dancing at a youth conference."
Know what? I don't believe that.
There are four people processing behind her in what passes today for altar-thing gowns, one of them carrying what appears to be a modern-art, non-representational cross and others with candles. It's clearly a procession of some sort, and it is taking place in the vicinity of what appears to be a Novus Ordo altar-table.
Looks to me like they're starting Mass.
And there's no way that she is "a young girl". Take a closer look.