You can use this command to create a screencast using ffmpeg.

ffmpeg -f x11grab -s 800x600 -i :0.0 /tmp/screencast.mpg

This command uses ffmpeg to convert a regular video into 3gp format thats used in mobile phones

ffmpeg -i input_video.mp4 -s 176x144 -vcodec h263 -r 25 -b 12200 -ab 12200 -ac 1 -ar 8000 output_video.3gp

Original Article

FFMPEG command to mix an audio file with a video file to create a final video.

ffmpeg -vcodec flv -qscale 9.5 -r 25 -ar 22050 -ab 32k -s 320x240 -i 1.mp3 -i Meta.ogv final.flv

Linux command to convert a video file to PSP format using ffmpeg. After converting, copy the OutputFile to the video folder in your PSP.

ffmpeg -i "OriginalFile.avi" -f psp -r 29.97 -b 768k -ar 24000 -ab 64k -s 320x240 "OutputFile.mp4"

Convert FLV file to MPEG using ffmpeg

ffmpeg -i myFile.flv -ab 56 -ar 22050 -b 500 -s 320x240 myFile.mpg