1) @ 3:40, when I say that gamma comprises 95% of extant Plinian manuscripts, I should have specified that this was 95% of all extant Plinian manuscripts that contain the Vesuvian letters.
2) @11:20, the date of Biondo’s ms. should be ca. 1424-25.
3) @12:05, I think that mss. c and q have a ‘nou’ with a long macron reading because c° contained both the ‘non’ (with a long macron) from Valla, and also the ‘nou’ from R1472, and either in that ms. or in its descendants, scribes were trying to reconcile those two options. Mss. c and q were both presentation copies (and have a number of errors), so their scribes were just trying to copy in a nice way what they saw in their exemplars, c° and q°. They weren’t necessarily trying to construe ‘November’, though that is a possibility. In either case, ‘November’ was not present in some dusty ancestor. It was contrived first, explicitly, by the r-editor in R1472–} r°.