Near the beginning of this purportedly serious documentary, the narrator used the phrase "from whence".
At the same moment, I stopped taking the movie seriously. For the want of a nail, the kingdom was lost. In a similar way, this movie lost my full attention.
It's entertaining, but marred by sensationalism, and so riddled with teasers and myths presented as "almost-maybe-could be" facts that although worth watching, it may not be worth taking seriously.
It might be better to do some reading about the Grail in the encyclopedia first, for a solid background, before watching this movie..