Merge Multiple Video files to one with FFMPEG

Processing video for upload to Facebook building a nice Video Collage like PicPlayPost IOS

ffmpeg –i video1.avi –sameq video1.mpg
ffmpeg –i video2.avi –sameq video2.mpg
ffmpeg –i video3.avi –sameq video3.mpg
# so on for every file to be merged
cat video1.mpg video2.mpg video3.mpg | ffmpeg –f mpeg –i - -sameq video.avi

Research FFMPEG