I don't think anyone is required to use VBV, it's an opt in thing. Maybe Visa incentivises merchants to do though additional chargeback protection or something but their site says it's only at participating retailers.
As for Verisign, as far as I know they just issue SSL certs. SSL is a security protocol that uses a trusted authority (verisign, there are other) to guarantee the identity of participants in a transaction (usually just website hosts, clients don't need their identity verified usually).