I think how you can summarise it is by ratting their associate out, they gave the key break in the case.
IMO the testimony would be somewhat problematic on it's own, given they did not witness the rape, but rather claimed to have seen a video which could not be produced. But corroborated by the hair, and the victim testimony that the attack was taped, it is pretty strong IMO.
The problem regards the MM case, is they don't claim to have seen any evidence (as far as we know) - so its the classic crooks confession.