Portal Forbidden Testing Tracks is a mod 

Segmented Secret% - Portal: Forbidden Testing Tracks 

G-Man Shows up and Sends me to Hell 

Portal 2: Forbidden Testing Tracks Playthrough No Commentary (Epilepsy Warning!!!) 

A secret ending!? - Portal: Forbidden Testing Tracks 

Okay, that's actually kinda cool! - Portal: Forbidden Testing Tracks (Easter Egg) 

Portal: Forbidden Testing Tracks - The Good Ending 

Portal: Forbidden Testing Tracks - Баг с камерой 2 (Глава 4) 

He Interferes Everywhere 

Portal: Forbidden Testing Tracks - Получение софт-лока