Does anyone have the duo dance Song Xi and Crystal did together anymore? I overheard a video of the two of them dancing, and it was on an inside venue, not an open air venue

Songsy and Crystal didn't do a duo dance together, but they did perform Girlfriend with After School.

But I think you're looking for a dance that f(x) did when they first started out, Jump off+Freeze

Songsy and Crystal went on stage first, followed by the other members of the group, who also danced together.

These are two of the dances, because there were a lot of them in the early days

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These are two of the dances that were performed in the early days of the show.