Thanks for posting these pictures, I can now work out how it works (or rather doesn’t work !).
I saw this at the bike show in Germany - BUT not very impressed !
It was not up to the same standard of design I’d expect from Strida.
They had 3 broken and only one working !
The main disappointment for me is it only has limited adjustment … only about 10 - 12cm. It does not adjust all the way up and down the ‘seat’ tube. I was hoping that it could be used to share my Strida with my wife, without having to unscrew the seat clamps (or move pins). But for major adjustments the whole seat thing still has to be removed to move the pins ! Such a PITA ! 
It seems to work by slackening off the Quick releases, and then pulling out the aluminium red part, which should allow the seat to adjust up and down with the red bit staying fixed. In practice it is very difficult to use, the poor girl gave up trying to demonstrate it to me, but she let me have a go, and I found it just as bad.
The whole system sort of cantilevers off the red bit (in the picture) on just one of those pins used to align the regular Strida seat this seems to be the major flaw. The pins bend and break with this extra load, making the whole thing lock up.
I was very disappointed. NOT recommended 