The Under Eye Brightening Corrector in Fair/light color by Smashbox is a must-have product, according to Christina's video review. She expresses her excitement and love for this collaboration between Smashbox and Becca. Christina appreciates the convenience of not having to wear a full face of makeup every day and instead uses this corrector to brighten up her under-eye area. She mentions that a little goes a long way and loves that it is not drying. Christina recommends using it both with or without makeup, as it effectively moisturizes and brightens the under-eye area. Overall, she highly recommends trying out this product to achieve a natural, no-makeup look with well-moisturized and brightened under eyes.