Many images crop up throughout the trailer that probably don’t mean anything to people who haven’t read the books, and while we can’t state for certain what some of the clips mean, we can make some educated guesses.
One of these occurs around the 0:17 mark, where you’ll notice a man crying, while bringing a golden object up to his mouth. Based on the books, we’d venture a guess that this is Lews Therin Telamon. The only time this version of Lews Therin appears in the flesh is in the prologue to the first book in the series, “The Eye of the World.”
The scene takes place 3,000 years before the events of the main story kick off. Lews Therin is a male Aes Sedai, and therefore a wielder of the male half of the True Source, known as saidin. Why do we think this is Lews Therin? Aside from those big, blubbery tears, he’s holding what looks to be an Aes Sedai’s golden serpent ring. By the time the series kicks off, there aren’t anymore male Aes Sedai. Indeed, Lews Therin is one of the last (and arguably the reason for their dissolution).
Millennia ago, Lews Therin and his band of male channelers sealed the Dark One (the series’ principal Big Bad) in his prison at Shayol Ghul, thus bringing an end to the War of Power. In the moment of the sealing, however, the Dark One counters by laying his evil taint over saidin. Henceforth, any male born with the ability to touch the Source is doomed to go insane and destroy everyone and everything around him. Lews Therin himself goes mad and kills his family, which is likely why he’s crying in the scene shown.