The image produced by the camera is ... two-dimensional, but only one of the dimensions -- the one corresponding to the direction of the slit -- is spatial. The other dimension, corresponding to the degree of deflection, is time. The image thus represents the time of arrival of photons passing through a one-dimensional slice of space.
Be sure to watch the video; the researchers (understandably) can barely keep the grins off their faces as they explain that they can record photons in motion. Einstein would be freaking out.
(Somewhat related, check out these rapatronic photos from the '40s that capture nuclear explosions--using ten nanosecond exposures--just one ten-millionths of a second after detonation.)