Plot: Auditions in six cities brought more than 200 dancers to Las Vegas for the callbacks on "So You Think You Can Dance?" By the end of the two-hour episode, that group would be hacked to the 20 finalists -- 10 guys and 10 girls -- that will compete for the top prize this season. Host Cat Deeley promised the most competitive Vegas week ever, with the dancers being challenged each day in a different types of choreography