Movie Thumbnailer (mtn) saves thumbnails (screenshots) of movie or video files to jpeg files. It uses FFmpeg's libavcodec as its engine, so it supports all popular codecs, e.g. h.265/hevc, h.264, mpeg1, mpeg2, mp4, vc1, wmv, xvid, divx...
mtn is open source software. It should run on all operating systems which have gcc, FFmpeg, and GD, for example, Linux and Windows.
mtn works similar to "mplayer -benchmark -nosound -quiet -zoom -vf scale=420:-3,tile=2:2 -vo jpeg:outdir=. -sstep 60 file.avi".
mtn comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions; for details see GPL2.