ffmpeg -i exclusive.mp4 -vf "setpts=2.0*PTS" output.mp4

// low quality
 - increase speed
ffmpeg -i input.mp4 -vf "setpts=0.5*PTS,scale=640:-1" -c:v libx264 -crf 28 -preset veryfast -an output.mp4
 - same speed
ffmpeg -i input.mp4 -vf "scale=640:-1" -c:v libx264 -crf 28 -preset veryfast -an output.mp4

// convert to webm
ffmpeg -i exclusive.orig.mp4 -c:v libvpx-vp9 -crf 30 -b:v 0 -b:a 128k -c:a libopus exclusive.orig.webm

// crop
ffmpeg -i input.mp4 -ss 00:00:10 -c copy output.mp4