GREGMAT extreme quant question

A box contains 11 red cube, 22 identical blue cubes and 22 identical green cubes. What is the number of distinct ways one can take all the cubes out of the box so that all blue cubes are removed before all green cubes are removed?

I am still not able to understand this question even after watching the video, can anyone help me understand through a different approach?

Can you please link the video?

Is the answer \frac{55!}{11!*(22!)^2*2} ?