[Janusz]

If you don't have ffmpeg added to path, just copy ffmpeg.exe to folder where you have video files.

[dir]
 |- ffmpeg.exe
 |- video01.mp4
 |- video02.mp4
 |- video03.mp4

Extract to .ogg:

for %v in (*.mp4) do ffmpeg -i "%v" -vn -acodec libvorbis "%v.ogg"

Extract to .mp3:

for %v in (*.mp4) do ffmpeg -i "%v" -vn -acodec libmp3lame "%v.mp3"