We don't know exactly how the action went preflop, but we know some substantial betting took place, because there was around 17,000 in the pot when the dealer spread the flop. It was here that Forrest checked and his opponent in later position moved all in for 27,325. Forrest gave a mild shrug and pushed his stack in the middle for a call. Cards were then tabled, and it was Forrest who was ahead.
Forrest was well out in front, but anything can happen as you will see. The on the turn gave Forrest's opponent a flush draw to go along with his king draw. As long as Forrest could avoid these outs then he would shoot up the chip counts and have more than a healthy stack to make a deep run. Indeed a spade did come as the made its presence known on the river.