Very strange thing

Hey guys!
Today I seen something I never seen before (and I play about 1,5 years now)... It was after a clan match. The clan match was very hard and we think that the others used wallhacks.
So we lost it. And after the last round everyone of us saw something on his desktop (dunno if its the right word for it).
It was something like an animation which said "~name of the clan~ has won this match". It looked a bit like the animation which says "Crossfire" at the end of this trailer: http://www.youtube.com/watch?v=-6hu96Z1mss
The problem is it went to fast so I couldnt take a screen and I also couldnt remember the clan name, cause they left immediately after the match.

My question is: Is this hacking? Or is this a special plugin?

Greetz ded