said by The Doctor:
If we assume only one user logged into netflix this would not cause much of dent but multiple users using netflix would increase usage.
It would have taken quite a few concurrent SD streams to bottle-neck a 16Mbps connection. And even if they were somehow saturating the 16Mbps connection with SD quality Netflix, a 56% increase in speed wouldn't translate to a 200%+ increase in usage. The math just doesn't work that way.
So again, if they haven't changed how much they watch Netflix, it's very unlikely to be the cause of the drastic increase in monthly internet usage.