It shows how NS5B, an RNA-dependent RNA polymerase, has been identified as the core of the replication complex - which possibly explains why sofosbuvir is a constant DAA throughout the treatments - working in tandem with various other inhibitors possibly selected through trial results on the basis of genotype. Of course not being educated in this field - my hypothesis could be total horse s---t. The video is superbly designed and medical training has moved to a whole new level with current technology.