“Best Christmas Ever” is a whimsical holiday short from Disney, directed by Taika Waititi, that follows a young girl whose simple Christmas wish springs unexpectedly to life. What unfolds is a heart-melting, gently funny story about imagination, friendship, and the little bits of magic that sneak into our lives when we least expect them. Yes, it’s a bit of an ad for Disney, but it’s charming, uplifting, and just the right kind of sparkle for the season.