The first wallbang you should use the edge of the wall to line up your shot.
The other 2 wallbangs you will just need to practise.
This video is mainly just to let you know you CAN shoot through them if the situation is right. It's not really a guideline video.
I have never seen anyone do the first wallbang in the video, the other 2 are quite common.
Rank: GE FOR TOO LONG