So the 3rd and 4th stakes are green and black, the green stake increases the ante scaling by 25% and applies the previous stakes that are the white stake (which gives 12.5% increased ante scaling) and the red stake (which gives 12.5% increased ante scaling). So now we have 12.5% (white stake) + 12.5% (red stake) + 25% (green stake) = 50% increased ante scaling making the blinds on ante 2 have 1200, 1800, 2400 (boss blind).
50% of 800 (800 being the base chips required without stakes) = 400 -> 400+800 = 1200
50% of 1200 = 600 -> 600+1200 = 1800
50% of 1600 = 800 -> 800+1600 = 2400
The black stake gives increased 25% scaling but with the other stakes applied (white, red and green) it goes to 75% increased ante scaling.
Tell me If I something confuses you...