"the length of film used in a scene, etc.," 1916, from foot (n.) as a measure of length + -age. Earlier used to describe a piece-work system to pay miners.
they had stock footage of lightning, tornados, and hurricanes
he edited the news footage
foolocracy
fool-proof
foolscap
foosball
foot
footage
football
foot-board
foot-bridge
foot-dragging
footer