This is from World Dj championships. DJ's are prepering for this in adwance. ussualy is like one man show so having four of them in the same time just playing and being in time is just amaising! long hours of practising and selections of tracks.
if you like that, check out this dj:
https://steemit.com/music/@djnarcoticdust/one-of-the-most-technical-skilled-dj-s-in-the-world-and-you-thought-you-are-a-dj