Hey Arnold! (found pitch pilot of Nickelodeon animated series; 1994)
From The Lost Media Wiki
Before Hey Arnold! became a cult classic TV show that aired from 1996 to 2004, Nickelodeon created a 9-minute pilot episode in 1994. It was never aired but it was only released on the theatrical release of Nickleodeon's first ever live-action movie, "Harriet the Spy", and wasn't included on the VHS release. After 13 years of being lost, the pilot episode was finally uploaded on YouTube in 2009.
The episode was remade as Season 1, Episode 18b "24 Hours to Live."