It's easy. Make sure to film other people on that video, with their pings shown. If there's only one having such issues, and his ping/loss/lag are not different' from others, thats self-explanatory.
First and Fourth is pure cheating (especially last, on first one he didn't ping his target, and other folks are kinda far away - but there's no sudden noticeable "jumps" among them),
Second shows that not just his target was jumping all over the place, but also Eagle on his left (0:16-0:23). Either that Eagle was cheating as well, or server was lagging.
Third shows rather "light" jittering, can't say what it was. (but could be cheating, as well, since that neutral Sabre doesnt show such "feats").
P.S.2 - try to fight while GRN is fighting BAF in Leeds, with Outcast having event with IMG at same time, in Taus, and you'll likely notice lags even in 1v1 fight, with nobody around.