Also not an expert, but since videos are transcoded as key-frames and changes applied to those key frames, I don't think it's as simple as segmenting something like a CSV. Transcoding is probably required just for the segmentation process. Putting it back together might be easier, but the final output file might also be larger because of overhead.

Media companies are already taking this approach using ffmpeg, AWS Lambda, and AWS Step Functions. I heard from two companies using such approaches at AWS re:Invent in October 2017, so it's definitely possible.

Rolling your own approach like this is certainly more complex to build/maintain than using Elastic Transcoder though.

Neither am I. It's pretty simple to do though, and the performance of the steps that aren't encoding are a lot quicker as it's mainly just copying the encoded files to an intermediate format, and then concatenating those together.

ffmpeg -i "file.mp4" -ss 01:16 -to 02:16 -c:v libx264 -crf 32 "newFile.mp4"

ffmpeg -i "file.mp4" -ss 02:20 -to 02:45 -c:v libx264 -crf 32 "newFile1.mp4"

ffmpeg -i "newFile.mp4" -c copy -bsf:v h264_mp4toannexb -f mpegts temp.ts

ffmpeg -i "newFile1.mp4" -c copy -bsf:v h264_mp4toannexb -f mpegts temp1.ts

timeout /t 5 /nobreak

ffmpeg -i "concat:temp.ts|temp1.ts" -c copy -bsf:a aac_adtstoasc "Finished.mp4"