One-liner to concat a bunch of video files into one. Grabs .mov, .mp4, and .mkv, sorts them, builds the concat list, runs ffmpeg, and cleans up.

find . -type f \( -iname \*.mov -o -iname \*.mp4 -o -iname \*.mkv \) -printf '%P\n' | sort -V | sed 's/^/file '\''/g' | sed 's/$/'\''/g' > fl.txt; ffmpeg -f concat -safe 0 -i fl.txt -c:a copy -c:v copy output.mp4; rm fl.txt