Either you're trolling or just sadly ignorant. I'll say if you think there are 65,000 characters on screen at any point in that video you need your vision checked. The rest, well you either know how they achieved those visuals or you don't and I'll just leave you to your ignorance.
Way to downplay the technical mastery of that game. Yes, the AI is dumb, but what they have done is incredible with the hardware at hand. Anyway, what RJC571 said was to counter the 1-2 enemies argument with an extreme example that maintained 60fps.