You can choose the release mode for photographs taken in movie mode (0 Shooting Movies (b Mode)).

Option Description
U Single frame The camera takes one photograph each time the shutter-release button is pressed. Regardless of the option selected, a maximum of 40 photos can be taken with each movie.
c Continuous The camera takes photographs while the shutter-release button is held down; the length of time available for the burst is shown in the shooting display. The frame rate varies with the option selected for Frame size/frame rate in the movie shooting menu. Only one photograph can be taken at a time while movie recording is in progress.