BSPEMore toggling from gr:m... with the name "curving bullets" LOL.
http://tf2center.com/profile/76561197986941186
http://ugcleague.com/players_page.cfm?player_id=76561197986941186
https://www.youtube.com/watch?v=B_a_TsjBNDQ
From tf2center: http://sizzlingstats.com/stats/382538, tick 68000
slowed down the end part: https://youtu.be/YEskdUohmtU
The tracking in the 2nd video doesnt even look that weird to me and it doesn't look like he's actually hitting them for that much compared to what you'd expect.
However the twitch to the sniper behind a wall at 0:11 in the first vid is suspicious as fuck.