It was most likely a 4×5 Graflex Speed Graphic used by photographer David Burnett. That camera has a distinctive vintage press-camera look, often with bellows, so it would stand out among modern digital gear and fit your description well.

Another possibility mentioned was a large dual-camera or robotic rig used for 3D/video capture, which can also look bulky and unusual from a distance. But if what you saw looked specifically like an old-fashioned still camera, the Speed Graphic is the better match.

So the best identification from the available answers is: a Graflex Speed Graphic large-format press camera, likely David Burnett’s.