At 2.30 to 2.48 he idled because he was literally getting owned and is plenty of time to toggle an aimbot on. It looks like it failed the first time so he stopped again at 3.40 and that's when the owning from him begins. Right after the second time he idled, he made the first snap with the minigun and it seeked perfectly by staying locked in the target, which you can see at 3.58. At 4.04, I can clearly see the aim being locked perfectly on the player which ends up in a quick kill using the minigun again.
At 4.51, I see the first snap which shoots the flakcannon simultaneously, new aimbots do exactly that, by locking at an enemy from a certain angle and shooting the weapon at the same time. His aim stays locked on the target until the first firing animation sequence of the weapon is done and starts missing all the shots that followed.
At 6.56, there's another snap but misses the first shot, maybe due to ping delay, but hits the player 3 times in a row while staying perfectly locked on the player causing another easy kill. Right at 7.13, he does exactly the same thing again with the shockrifle but its really hard to visually detect it since his aim was very close to the target when the snap happened.
The most obvious snap I saw happened at 9.20 when he was goofing off pulling some lift jumping combos. Right at that time he alt-fired to start a combo but his aim instantly snapped at the player when the player had just come out from behind a wall, it looks like he was trigger happy at that moment and gave him away.
The second obvious snap was at 10.06 while he was starting a combo above the kicker on the left side when the player just popped in from under the bridge on the right side, his aim instantly snapped downwards to the right side directly at the player but missed the shot probably due to ping delay. Ya, it happens.
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If you watch closely to his camera movements and turns, it is pretty clear that hes using a very slow mouse speed. It looks like the mouse sensitivity is set to 1.0 or less. From many years of playing fps games I can tell you one thing, snapping instantly the way he was doing is quite impossible, specially if the aim angles right at the enemy perfectly and doing a shot simultaneously. There's a big difference between lucky shots and cheat shots, and none of those I mentioned were anywhere close looking like lucky shots.
I just wanted to mention that the other guy was doing exactly the same as this hirez guy but for some reason he wasnt being demoed. His radaring was too obvious throughout the beginning of the video and he also showed instant turns that killed as well from impossible angles. The only instant turn I was able to catch from ezskillz happened at 11.19 where he instantly turned at the enemy releasing the rockets simultaneously, perfectly compensated at the direction the target was falling to.
Well, I hope this helps understanding the difference between skills and cheats. And I took the time checking this out to explain how to capture a radar/aimbot cheat visually so you know what to look for when watching a demo or clip.