Is there a lawyer in the house?
I'm puzzled. If it was legal for them to distribute these videos via Pirate Bay then presumably it was legal for others to download them once there. If it wasn't legal to put them there (*), surely they are opening themselves up to a much larger lawsuit from the actual copyright holders.
Also, is this not a possible defence for the downloaders? If, for example, I buy a CD on the High Street and I later find out that it is counterfeit then, yes, I have a duty to stop using the CD, seek compensation from the shop, and inform the police. However, if I do all those things then I would not expect the copyright owner to have much of a case against me. (Mens Rea and all that.)
(* I'm guessing it wasn't, since the music industry has spent about 30 years trying to enforce this very point.)