ffmpeg

- Cutting a video

ffmpeg -ss 00:01:00 -to 00:02:00 -i input.mp4 -c copy output.mp4

-i :  input file
-ss :  start time
-to :  duration
-c copy :  Trim via stream copy which is very fast.

- Burning a subtitle

subtitle="subtitles=subtitle.srt"
font="force_style='Fontsize=24,PrimaryColour=&H0ffffff'"
filtergraph="${subtitle}:${font}"
ffmpeg -i input.mp4 -vf $filtergraph -c:a copy output.mp4

The colour format is &HAABBGGRR (alpha, blue, green, red).
The alpha is inverted: 00 is fully opaque, and FF is fully transparent.

- Adding images

ffmpeg -i input.mp4 -i 1.png -i 2.png -i 3.png \
  -filter_complex "[0][1]overlay=x=0:y=0:enable='between(t,284,292)'[v1]; \
  [v1][2]overlay=x=0:y=0:enable='between(t,383,387)'[v2]; \
  [v2][3]overlay=x=0:y=0:enable='between(t,1779,1783)'[v3]" -map "[v3]" -map 0:a  output.mp4