Prisoner Hat Puzzle - who will shout first?

4 prisoners are are given a hat each from 2 blue and 2 yellow hats. Find out who will shout first and declare his own hat color?

All know that there are 2 blue and 2 yellow hats.
They do not know their own hat color.
4 can see 3 and 2s hat color
3 can see 2s hat color and 1 can see only the wall.
No speaking or touching. No mirrors. No movements.

Please check out the video which explains the solution to this problem.