What three things are in the world's system according to the verse Les is teaching?
Scripture lists three things in the world's system: the lust of the flesh, the lust of the eye, and the pride of life. These correspond to Christ's temptations—bread for hunger, the appeal to the eye at the temple pinnacle, and Satan's offer of power over the kingdoms—and they aim to grab hold of us so we lose control.
Les explains that verse 16 describes "all that is in the world, in this world's system": the lust of the flesh, the lust of the eye, and the pride of life. He flashes back to Matthew and asks what Christ's first temptation was—bread, because He was hungry—so He suffered the temptation of the lust of the flesh. The second was the appeal to the eye, since the vast crowd would have witnessed a miraculous plunge from the pinnacle of the temple, a temptation to appeal to the things of the eye. The third is when Satan says, "I'll give you power over all these kingdoms." Les also goes further back to Satan's appeal to Eve, which began with "Look at the fruit"—appealing to the eye. He illustrates the danger with the slot machine story: don't let the dumb thing grab you, don't partake to the place where these things get a hold of you and you can't let go, because that is what the things of the world do, and that's what the world's system is trying to do—literally grab us and make us lose control.