The Mexican comedy "Cuando Sea Joven" puts a sweet spin on the idea. A 70-year-old grandmother, played by the legendary Veronica Castro, transforms into her 22-year-old self after being photographed in a mysterious studio. The film is based on the South Korean comedy "Miss Granny" and opened over the weekend in just over 300 theaters. It's charming, accessible and deserves to find an ever bigger audience.