Truncate

Using ffmpeg.

Without reencoding (there need to be enough I-Frames in the stream):

ffmpeg -ss 00:00:00 -t 00:22:30 -i input.mov -acodec copy -vcodec copy output.mov

With reencoding:

ffmpeg -ss 00:00:00 -t 00:22:30 -i input.mov output.mov

Note that putting -ss after the -i is more accurate but slower.

Concatenate

ffmpeg  -i 1.mov -i 2.mov -vcodec copy -acodec copy both.mov

Not supported as of ffmpeg-3:20080706-0.3lenny2

ffmpeg -i Input.mov -vcodec copy -acodec copy -metadata "Create Date=2013:03:25 14:32:28" Output.mov

Using ffmpeg scene change detection.

Output a showinfo message if scene difference is greater than, say, 4%:

ffmpeg -i tmp.mp4  -filter:v "select='gt(scene,0.04)',showinfo" -f null -

Then truncate using the timestamps.