[Ffmpeg-user] it's possible to merge 2 file video

http://lists.mplayerhq.hu/pipermail/ffmpeg-user/2006-March/002526.html

ffmpeg does not support appending of videos natively. On Unix or Linux
or MSys you can use something like (untested!)

cat utc_1434.mpg utc_1800.mpg | ffmpeg -i - -acodec copy -vcodec copy
jef2.mpg

(concatenates and remux).

On WXP you could use "copy a.mpg/b+b.mpg/b c.mpg/b" then remux with ffmpeg.

p.s. ffmpeg -i jef2.mpg -target ntsc-vcd jef2vcd.mpg is still needed to remux!!