Even in the smaller GBCs (like GBC 20 in this video) we have incorporated neat little mechanisms to detect and control the GBC Balls. Always nice to see our GBCs all over the web. Thanks for sharing with us Paweł Turalski.
Try the GBC 20 Mining Lift for yourself:
https://pv-productions.com/product/lego-gbc-20-42049-building-instructions/
See our full GBC catalog with building instructions: https://pv-productions.com/product-category/lego/