@echo off
for /f %%f in ('ls -1 *avi') do c:\mplayer\mencoder.exe -ovc copy -nosound %%f -o %%~nf.dump
for /f %%f in ('ls -1 *wav') do c:\mplayer\ffmpeg.exe -i %%f -acodec libmp3lame -ar 44100 -ab 64k -ac 1 %%~nf.mp3

avi
for /f %%f in ('ls -1 *dump') do c:\mplayer\mencoder.exe -ovc copy -oac copy -audiofile %%~nf.mp3 %%f -o %%~nf.2.flv
flv (couldn’t find a way to remux without reencoding)
for /f %%f in ('ls -1 *dump') do c:\mplayer\mencoder.exe -vf scale=720x576 -af volume=+16db -ovc lavc -lavcopts dia=2:precmp=2:cmp=2:subcmp=2:vcodec=flv:vbitrate=1024 -lavfopts i_certify_that_my_video_stream_does_not_use_b_frames -of lavf -ffourcc FLV1 -oac copy -audiofile %%~nf.mp3 %%f -o %%~nf.2.flv

ls is a dir replacement from here