The English dub for this episode is available through the Crunchyroll Dragon Ball Z collection . Trunks Saga / Androids Saga.
After Goku arrives back on Earth, the mysterious young man who defeated asks to speak with him privately. Key Revelations Dragon Ball Z (Dub) Episode 122
He explains that in his time, Goku dies of a rare heart virus, and most of the Z Fighters are killed by two ruthless Androids. The English dub for this episode is available
