While Goku is on Snake Way, the other Z-Fighters (Yamcha, Tien, Krillin, Chiaotzu) train in a virtual simulation at Kami's Lookout.
Krillin tries to cheat by taking shortcuts, and Master Roshi motivates Goku by telling him his grandfather once did the same training. DragonBall_Ep_017.mp4
If your file is from the DBZ era, it takes place during the Saiyan Saga . While Goku is on Snake Way, the other