Nikon D780 DSLR Camera (Body Only) - Manual (Page 318)

272 Options for Movie Recording and Editing
Trimming Movies
To create trimmed copies of movies:
1
Display a movie full frame ( 0 353).
2
Pause the movie on the new
opening frame.
Play the movie back as described in
“Viewing Movies” (
0 53), pressing J
to start and resume playback and 3
to pause and pressing 4 or 2 or
rotating the main command dial to locate the desired frame.
Your approximate position in the movie can be ascertained
from the movie progress bar. Pause playback when you
reach the new opening frame.