Something about an algorithm designing circuits that shouldn't have worked, but did. I might be mixing another story, but I think it was using electrical interference from an outside source to accomplish its task.
I think he was saying it was a genetic algorithm on an FPGA board. It was designing circuits by simulating them (in hardware), but if you actually tried to build the design in a custom chip it wouldn't work because you'd only have kept the circuit logic, not the interference properties.