Quagmire
You're correct, it was a Buffalo. It was in the early '70s I think and there was a demo in New York of what they would do in a major emergency.
DeHavilland Canada sent a contingent, landing a Buffalo in a baseball stadium and taking off again (impressive since home plate to the outfield fence is just over 300 ft!). They also had a Twin Otter land on a dock.
Another DHC stunt was landing a DHC-4 Caribou on an iceberg. Probably the most dangerous one they tried.
The DeHavilland pilots would demo short field performance by putting the props into Beta (reverse thrust) on approach and come in very steeply. You had to time it just right to get the energy back up for the flare. The famous Buffalo crash at Farnborough was an example of getting it wrong.
The real controversy about that one was that 3 people ran out of the aircraft - the pilots had taken a pax! I heard the Captain was later seen scratching a living by ferrying single engine Cessnas across the Atlantic.