This is very basic and at least there should be a readme file in the unzipped folder for instructions. I have done a search on “How to update firmware” with no results. For coders, a standard procedure is to place a readme.txt file within the install folder. There is nothing in the manual nor FAQs about updating the firmware.
For Windows, I was looking for an exe file or something like that for the update…
Updated: I found the video in a forum post - which should also be where the download file is located - at least a link, and a readme file in the download.