Taking this actually seriously, which might be kind of hard, because my bet would be he was just trolling, this doesn't feel like an aimlock.
Aimlock usually fixes the crosshair on a pretty specific pixel (point on the screen) and stays there for as long as the aimlock is active. In your video you can clearly see discrepancies and flickering of the crosshair especially in your slowed down parts, this wouldn't happen with an aimlock and suggests it's just his aim control.