Thanks for the tip offs and links, it got in the way of seat height adjustment so couldn’t figure why something would be there =D I see now the two stages of adjustments. Since regular seat tubes are clamp friction and this one was large surface area despite being plastic I didn’t worry too much, but it was only a short test.
A little strange to provide a CD/DVD user manual for a portable mechanical device, without printed assembly instructions etc. as I’ve even had an assembly manual included in a cheap Chinese single speed bike that I expected nothing with. The YouTube usability review for instance could have had all the user wisdoms in a quick assembly and reference guide with all the scenarios, but I guess that might take another 25 years to come about =D