I found https://github.com/mifi/editly to be an intuitive frontend for this type...

bbkane 4 months ago | parent | context | favorite | on: Make timelapses easily using FFmpeg

I found https://github.com/mifi/editly to be an intuitive frontend for this type of task - I used it to create a montage of several clips and was able to easily adjust parameters around timestamps and such to get the montage perfect