Haven't watched yet, but generally you want to hit your "end game" composition and then hulk smash. For Protoss, this means get up to range colossi, high templar, and archons (if he has tanks, instead of HTs go for some air units, like temptests or VRs). Rely on the range of your colossi to kill his shit further than he can shoot, or the temptests with their infinity range to kill stuff. Other than that, expand to every base.