find . -type f -iname '*.mp4' ! -iname '*.compressed.mp4' -exec bash -c '
for f; do
out="${f%.mp4}.compressed.mp4"
ffmpeg -loglevel error -nostats -y -i "$f" \
-map 0:v:0 -map 0:a:0? \
-vf "scale=if(gt(iw\,1280)\,1280\,iw):-2" \
-c:v libx264 -pix_fmt yuv420p -profile:v high -level 4.0 -preset veryfast -crf 28 \
-c:a aac -b:a 128k -movflags +faststart "$out"
done
' _ {} +