FFmpeg Video Capture
Location - Sets/Preview

If the Media Type is a movie file with a supported encoding format (mpeg or windows media version 1-8), clicking + Crop Thumb to the right of the thumbnail will load the Capture Video Screenshots page.

Here you have the option to navigate the movie and capture the desired frame. You can move ahead (or back) in increments of 1, 10, 100 and 1000 frames at a time.

Once the Create Thumb from This Frame button is clicked, the image will be resized to correspond with your general thumbnail size setting.