Canon EOS-1D X Mark III EOS-1DX Mark III Advanced User Guide - Page 440

5. Save the image. Select [ ] (1). The save screen will appear. To save it as a new file, select [New file], or to save it and overwrite the original movie file, select [Overwrite]. On the confirmation screen, select [OK] to save the edited movie and return to the movie playback screen. Caution Because editing is performed in approx. 1 sec. increments (at the position indicated by [ ] at the bottom of the screen), the actual position where movies are trimmed may differ from your specified position. Movies recorded with another camera and RAW movies cannot be edited with this camera. You cannot edit a movie when the camera is connected to a computer. 440