Create A Video Thumbnail Image With ffmpeg

You can easily create video thumbnails from the command line with ffmpeg. Although, you'll first need to install the library.

On OSX:

brew install ffmpeg

Specify your input video file, a position(ss), the number of frames(vframes), and an output file:

ffmpeg -i 'input_video.mp4' -ss 00:00:01.000 -vframes 1 'thumb.png'

Check out the ffmpeg docs here