Duplicate tnt machine

Part, I recently saw a tutorial on youtube tnt machine for tunneling but tnt duplicates.
Playback steps are included in this video and download map from description:
https://www.youtube.com/watch?v=0r7fVRqKjcg

I think it is not fair but I may be wrong, I also do not know what comment the creators have on it and I have not seen a similar topic.