I apologize if I am being annoying here, but I am not sure whether you and I are on the same page. Because my bees are defensive, I also built an enclosed system almost identical to yours, and my tubes are 10cm longer than yours (60cm per tube). The torque generated when moving the lid off the harvesting jar and onto a new empty jar needed lots of supervision of the Flow tube at the frame end and at least 2 people, even for one tube. Just a shame to lose honey and/or kill bees. 
Here is the thread where we show some video of our harvest (not the whole extraction, though), in case you are interested:
The second video, further down the thread, shows us extracting 2 frames at once. It was tricky handling the tubes (so that they didn’t dislodge the next door tube) when the time came to switch the jars. 