FFMpeg can do this by seeking to the given timestamp and extracting exactly one frame as an image, see for instance:

ffmpeg -i input_file.mp4 -ss 01:23:45 -vframes 1 output.jpg

Let's explain the options:

-i input file           the path to the input file
-ss 01:23:45            seek the position to the specified timestamp
-vframes 1              only handle one video frame
output.jpg              output filename, should have a well-known extension

The -ss parameter accepts a value in the form HH:MM:SS[.xxx] or as a number in seconds. If you need a percentage, you need to compute the video duration beforehand.

FFmpeg can do this by seeking to the given timestamp and extracting exactly one frame as an image, see for instance:

ffmpeg -i input_file.mp4 -ss 01:23:45 -frames:v 1 output.jpg

Let's explain the options:

-i input file           the path to the input file
-ss 01:23:45            seek the position to the specified timestamp
-frames:v 1             only handle one video frame
output.jpg              output filename, should have a well-known extension

The -ss parameter accepts a value in the form HH:MM:SS[.xxx] or as a number in seconds. If you need a percentage, you need to compute the video duration beforehand.