I think the guy in the OP's video would probably be pretty comfortable if Gnosticism was around in any pervasive form anymore :)
The thing with Christianity, is as Iniquitous Opheliac pointed out, it was a label applied to Jesus and his Jewish followers, long after the fact. And even after the label applied, it was never a monolithic one. There were many different churches, preaching many different doctrines and gospels. The two main "factions" of Christianity, before the Catholic vs. Orthodox schism, were Alexandria and Rome.
The proto-Catholic church that would eventually win the day was a somewhat large and rather influential group. Equally so, was the Christian community at Alexandria, which was much more diverse, and included in the most common body of its beliefs were the so-called "Gnostic Gospels." Long story short, at the council of Nicea (again, nice work, Opehliac :) ) and after much anti-Gnostic propaganda, the Church of Rome essentially won the day. History may have been very different if some of the books that were excluded found themselves in the canon, and vice versa.