One woman has the stacking task, while her sibling coaches from a distance, able to see the precarious column from a different angle.

After two glasses are stacked and with 35 seconds to go, she fills a third with the decorations. "OK, that third one is just slightly off -- just slightly," advises her sister.

She straightens it and adds the final glass with 15 seconds left. The column stands alone for three seconds -- voila! Level eight complete, and $250,000 won!