his ping was nearly around 450-480
and his ping strangely were moving from 160-180 to 450-480 in one second
I have thoroughly watched the video. As you said above, to me it seems like this horrendous lag might be due to combination of high lag, and jitter. And by lead aim, you were able to land some of the shots on him successfully.
As long as ping is under 500ms and not exceeding the limit specified by developers, I think its fine.. But,
I am going to watch this guy and try to investigate it further along with other staff and try to come up with conclusion.
If you see him, kindly record some more evidence and post them again on forums with reference to this report and it will be entertained diligently altogether.
Thank you for reporting.