This does not make sense to me. As far as I got it, bottom pipe is isolated from top 2 and just controls valve of the top 2 pipes. So, when air from bottle goes into left "liar" trough top 2 tubes of the right one it should just stop there. There is no way air can get to the middle one and also return to the right one to close/open it.
I hope somebody can explain this to me, because I'm starting to loose my mind a bit over this.
See, in the video it's clearly seen that input air pipe goes only into A cylinder's input pipe. B and C does not receive air at all! Also it seems that B and C are closed initially, while A is open. And I can't really see any springs that you mentioned either. This is what really frustrates me. How B and C can operate if they are not even connected to air supply?
OK, I'm feeling really embarrassed now. Are this tubes actually fused together? The problem is, Theo holds his finger over it almost all the duration of operation and it really seems that this 2 tubes are separate... In this case, Transistor's schematic is correct and my problem is solved.