Avidemux can extract Vorbis audio track. But the track is not playable:
http://www.avidemux.org/admWiki/doku.php?id=tutorial:save_only_audio (http://www.avidemux.org/admWiki/doku.php?id=tutorial:save_only_audio)
Is there a way how to put that stream in some audio container?
Or can Avidemux delete only video stream in some video file?
P.S.
I have managed it with avidemux by saving that webm video with mkv muxer and opened it in
http://www.videohelp.com/tools/MKVtoolnix (http://www.videohelp.com/tools/MKVtoolnix) and deleted video stream there and muxed as .mka
Could do that Avidemux?