Команда склейки видео в ffmpeg
ffmpeg -i AW_V_2.mkv -i AW_V_2_1.mkv -filter_complex "[0:v] [0:a] [1:v] [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" AW_V_2_f.mkv
ffmpeg -i AW_V_2.mkv -i AW_V_2_1.mkv -filter_complex "[0:v] [0:a] [1:v] [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" AW_V_2_f.mkv