Borrini finds Philip Rohr's 1679 De masticatione mortuorum, and I can not help being amused by how dramatically they present the book, even claiming that it contains 'an ancient ritual' with 'instructions for killing an undead corpse'. They then cut to Borrini, who without further ado identifies the masticating dead with vampires.
In the book accompanying the documentary, Vampire Forensics: Uncovering the Origins of an Enduring Legend, Mark Collins Jenkins includes a few references to the contents of Rohr's book (p. 140f): 'Rohr went on to cite a certain Adam Rother, who claimed that, as pestilence ravaged the German univesity town of Marburg in 1581, the dead in their graves could be heard uttering ominous noises from all over the town and surrounding countryside.'
Rohr actually writes: 'Sic Adamus Rotherus, Superintendens Martisburg. in Medit. de pest. meminit aliqvot cadaverum, qvæ Martisburgi, & in vicinis locis an. 1581. glocitarunt.' The reference appears to be to the book Piae meditationes et commonefactiones ex verbo dei/ Quas tempore pestiferae, luis, publice pro concione proposuit auditoribus suis Adamus Rotherus published in Wittenberg in 1584, and Rohr just says that Rother(us) in his book remembered that a number of cadavers cackled in Marburg and its neighbourhood.
It is interesting that he uses the word glocitarunt to describe the sound of the dead, as this signifies the natural sounds made by hen (glocio or 'glocito', to cluck or cackle). Other authors have tended to describe the sound as similar to that of pigs.
Anyway, the documentary is, of course, about the archaeological find of a skeleton with a stone in its mouth, which lead Borrini and others to speculate that it might be archaeological evidence of beliefs in vampires in Venice. One single sentence in Rohr's book, apparently, led Borrini to this hypothesis: 'Alii hoc medium non satis tutum rati, etiam mortuo, priusqvam ejus os claudatur, lapidem & nummum ponunt in ore, ut si in sepulcro mordere incipiat, lapidem & nummum inveniat, & ab esu abstineat.' I.e.: Others regard this means as not quite safe, so before the dead person's mouth is closed, they place a stone and a coin in the mouth, so that if the corpse begins to eat in the grave, it finds the stone and the coin and abstains from eating. One should note, that it says here that the mouth is closed, after the stone and coin have been placed in the mouth, so one must assume that the stone is just a small one and not a brick like the one found in Venice!
And by the way, Jenkins obviously quotes from the translation by Montague Summers in The Vampire in Europe, as he says that the stone and coin is placed 'in the cold mouth', the coldness of the mouth being an embellishment added by Summers.
In any case, as Jenkins writes: 'When Matteo Borrini read that, he understood why the brick had been thrust into the mouth of ID6: This person was suspected of being a vampire.' And the rest is history: The vampire theory made its way to global media, and in turn inspired a piece of vampire fiction!
At least I suppose that is why we find vampires in Venice in an episode from 2010 of the ongoing Doctor Who TV series, as you can see in the trailer below.
And as is often the case, fiction itself creates a myth, in this case an elaborate piece of science fiction as presented in the following video. Bricks thrust into the vampire's mouth, however, do not have a place in this mythology.
Some further surprises from the Doctor's time travel to Venice can be found in a making of featurette, and the National Geographics documentary is available on DVD, cf. the review here.