many thanks for posting Neil - very interesting.
my own thoughts on the narrator's suggestion of 'something similar to a shot glass', would be that bearing in mind the projecting rim then might this be more akin to a jelly rather than a drinking glass.
I would have thought that placing a rim with that profile to your mouth would be uncomfortable.
It may be very likely, but there is another possible connection to the expression 'shot glass'...........
G. Bernard Hughes (English Glass for the Collector - page 215) - in reference to glass related to 'millefiori work and other associated paperweights', says.......
"In addition to paperweights a variety of glass objects may contain colourful millefiori decoration, including small tazzas for wax wafers, shot glasses for holding writing quills, inkpots etc. etc."
And Newman - 'An Illustrated Dictionary of Glass' - page 282, provides an entry which confirms the existence of such things, adding that such pieces were filled with lead shot to support and clean quill pens.
I wasn't aware that there were such things as small glass containers for quills that were known as shot glasses.
I'm still inclined to think the piece in the film is more likely to be a jelly glass, but could be wrong.