No, those statistics exclude merge commits . Here's the command that generated those outputs [1]:
git shortlog -ns --no-merges v11..HEAD | head -n15
git shortlog -ns --no-merges n2.4..HEAD | head -n15
Michael Niedermayer is an EXTREMELY prolific dev who has been banging out FFMPEG code for more than a decade. It's by no means a one-man show, many other devs make large and valuable contributions - but in relative terms Niedermayer absolutely dominates FFMPEG, both in terms of personality and code output.