Top heavy rocks like that would be in a state of unstable equilibrium - they might balance for a second or two but if you even breathed near them they'd topple.
There is a clue on his website. The temperature was minus 5 C. The rocks look wet. I suspect there is a thin layer of ice between the rocks which overcomes the tendency to topple as long as they are finely balanced and held there while the ice forms. He does say if it's windy, they come down.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.