It's not crypto. It's a previously unknown language. From the paper.
It is feasible that the script is a deliberately constructed cipher designed to hide information of some sort. However, given the fact that the plant pages seem in practice to concern the plants depicted, presumably offering knowledge which was available to others already, it is more likely that the script is not aimed at concealment, but was instead constructed simply to write a language which had not previously been written down. To put it another way, if the underlying language already had a script (such as Georgian, or Arabic, or Greek), it seems highly unlikely that anyone would invent a whole new one merely to encode information about plants and nature which was already known.
The video is not pleasant to listen to, so I have not bothered.