Pentax K-X Operating Manual page 43

You can capture a single frame from a movie recorded with the/_-X and
save it as a JPEG still picture.
1
2
Pause the movie in Step 3 of "Playing Back Movies" to
display the frame to save as a still picture.
Press the INFO button.
The save confirmation screen appears.
3 Use the four-way controller (• •)
to select [Save as].
Press the
OK
button.
The captured image issaved as a new image.