There on USKO was many good clans like Hatred,Sex4Fun,NeverTown,Patriot and so on but i'm sure the posted one in the video wasn't even close to "the best clan".
I'm not really sure but in the inter-server war the clan who won the competition was Hatred(if i remember good) and the vs event won Odi from Heaven clan - Cypher.

Anw the topic it's to old,even so will be go on

Hmm nobody said tioc??? Usko first lol of ultima and felonkor, best pvp team work

It would be hard to say there's a clan that's the "best clan on USKO.."

But if we were to pick from our servers, I'd say in PK from my server (Xigenon) my old clan, PsychoticInfluenze was one of the best, if not the best.
PK 1: https://www.youtube.com/watch?v=uihxFsGymAw
PK 2: https://www.youtube.com/watch?v=KOhlL3Jaol4
PK 3: https://www.youtube.com/watch?v=vrOAonmS9-w

and if you want to go even further back than this, "NO" would be the best clan, with the ally clans "DontKnow" and "DontAsk"

and on orc nation, ofc, Legendz.

ciao.

''D2K'' is the best there