Here is a video compilation of various green flashes observed in Negril Jamaica. The camera used was a Sony NEX5N with a Canon 400mm lens on a tripod. We see green flashes often (the advantage of living on the western coast in the tropics) at sunset. It may even be raining overhead but clear off in the sea and we will see a green flash. But when the atmosphere is calm and mostly clear we get some great flashes.
The video has no sound and I do hope it is not too sliced up by the data compression.