Cat Deeley Reacts to Allison Holker Joining 'SYTYCD' and Bringing tWitch's Memory With Her

Cat Deeley chats with ET's Cassie DiLaura about Season 18 of 'So You Think You Can Dance,' premiering March 4 on Fox. The host reacts to former contestant Allison Holker joining the show as a judge and bringing her late husband Stephen 'tWitch' Boss' memory with her. Plus, Cat opens up about the show's changes for the new season and working with the other new judge, 'Dancing with the Stars' pro Maks Chmerkovskiy.