The first scientific writings that we know of (from either culture...) are astronomical observations, applied arithmetic (for things like building pyramids, as well as accountancy) and medical observations & treatments. The Greeks then took this further by systematising & analysing data on many different things, biological as well as physical & chemical. The programme made the point that a lot of our words for scientific processes come from the Greek - analyse, theory etc. This Greek knowledge & process was then transmitted via the Islamic world to Renaissance Europe and taken forward by new scientists in the Enlightenment era.
They spent a while looking at Newton's notebooks, which are kept at Cambridge. These (and other scientists' notebooks) evolved from the commonplace books that educated people would keep at this time into something closer to a modern lab book. Commonplace books were notebooks where someone would write down facts & quotations & such that caught their interest or that they wanted to remember. Newton's books started off like this, but soon became places where he wrote down what experiments he'd performed & what he'd observed - like diagrams of a particular prism set up & details of what he saw. Or an experiment where he stuck a wooden bodkin in behind his eyeball and deformed the curvature of the eyeball and recorded what that did to his vision ...
So the handwritten word was (and still is) important in the doing of science, in recording what you tried, what happened, what you think that means & what you'll do next. The printed word is important in the dissemination of scientific knowledge - relatively large numbers of identical books can be produced, and then not only can more people read them but also discussions can refer to specific things & be sure they're the same in the book their correspondent has.
Overall this was an interesting series, although at times it felt far too Euro- or British-centric. I guess this was partly because he was visiting British places that held early writings, and those collections are bound to be biased towards more local things.