The video shows what happens when a head gasket is compromised. As the engine is running and under load, there is coolant being expelled from between the cylinder head and the block surface.
Once the cylinder head was removed, it was evident that the coolant leak had been present for quite some time. The leak created corrosion trails running down from the cylinder head to the piston below. This corrosion that formed along the length of the piston wall compromised the piston rings and their seal against the cylinder wall. Looking further down into the cylinder at the top of the piston, it shows heavy pitting and metal erosion due to the head gasket leak. This engine required a total overhaul.