In the first few seconds, he is speaking to Dormin. Dormin has the power to control life and death, as you all may know. He tells the Wanderer he must kill the colossus to bring back Mono, but doing so is not a easy task. In a later moment of the video which shows the Wander riding Agro, it is referencing to the amount of time it takes to find the colossus. After he gets stepped on, he makes a joke about regenerating health which is also present in Shadow of the Colossus.
Nice explaining but they have to actually play to really get it though!!