You must use two metal pots.

If you don't have time, or you don't want to microwave defrost and overcook - this method is great !

You MUST use metal pots though. The Sciences behind this is essentially that metal works as a conductor for many things including heat. Metals conduct ambient heat which is enough to defrost a steak. Sandwiching it between two large metal surfaces, weighted by water, increases the surface area contacting the steak and the room temperature air, making the conduction more efficient.

Hot water or cold? It is judgment just water out the tap that's totally fine!