Pokémon "Pokémon! I Choose You!" (found original Japanese airing of anime series pilot; 1997)
When Pokémon finally went back on air in April 1998, four months after the infamous "Electric Soldier Porygon" incident, OLM edited the previous 37 episodes, slowed down the flashing lights, and never aired the original versions again despite no previous reports of the episodes causing seizures for anyone.
On April 2nd, 2013, the original versions were taken from sub group #pokemon-originals and uploaded to Hulu Japan. Since then, the sub group seems to have disbanded. Even then, however, episode one's original cut was not uploaded because Hulu replaced it with a new version that included advertisements for the Wii U before the episodes were put on the #pokemon-originals website. Because of that, the episode was still missing until May 2nd, 2015 when a fan group called Pokémon Peru once again uploaded the original cut in two parts.