You didn't check the audio format of the original file, did you?
You're telling avconv/ffmpeg to just copy the audio track into an mp3, but then it tells you that an MP3 audio stream is required as a source, otherwise it won't be able to perform a stream copy in the output file.
Also, looking at your stream mapping, it appears as ffmpeg/avconv is trying to convert the source h264 video stream to png (an image sequence of png files, perhaps?), so I would force it to completely discard the video stream using the -vn option.
For the sake of completeness, please post the complete output of the
ffmpeg -i the-Wolfgang-Press-A-Question-of-Time.flv
between code tags.