There are on average 24 to 30 frames in every second of a video. This means an image will switch to the next image at least 24 times every second. The minimum frame is 24 because this is when the human eye interprets the footage as smooth and without any cuts.
A Student from The American University of Paris took a totally different approach. He composed a video solely with still images shot with a Nikon D90 camera. I think the massive effort spent was worth it, as it turned out to be a creative piece of footage.