[FFmpeg-user] Unable to join audio and video files into 1 file

[jd1008]

$ ffmpeg -i 'Amis Raynaut-mUTtmdb4TCs.f171.webm' -i 'Amis 
Raynaut-mUTtmdb4TCs.f248.webm' 'Qntal - Silver Swan - 02. Amis 
Raynaut-mUTtmdb4TCs.webm'
ffmpeg -i 'Amis Raynaut-mUTtmdb4TCs.f171.webm' -i 'Amis 
Raynaut-mUTtmdb4TCs.f248.webm' 'Qntal - Silver Swan - 02. Amis 
Raynaut-mUTtmdb4TCs.webm'
ffmpeg version N-51556-ge278500 Copyright (c) 2000-2013 the FFmpeg 
developers
   built on Apr  4 2013 05:11:43 with gcc 4.6 (Debian 4.6.3-1)
   configuration: --prefix=/root/ffmpeg-static/32bit --arch=x86_32 
--extra-cflags='-m32 -I/root/ffmpeg-static/32bit/include -static' 
--extra-ldflags='-m32 -L/root/ffmpeg-static/32bit/lib -static' 
--extra-libs='-lxml2 -lexpat -lfreetype' --enable-static 
--disable-shared --disable-ffserver --disable-doc --enable-bzlib 
--enable-zlib --enable-postproc --enable-runtime-cpudetect 
--enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis 
--enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype 
--enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc 
--enable-libvo-amrwbenc --enable-version3 --enable-libvpx
   libavutil      52. 24.100 / 52. 24.100
   libavcodec     55.  2.100 / 55.  2.100
   libavformat    55.  1.100 / 55.  1.100
   libavdevice    55.  0.100 / 55.  0.100
   libavfilter     3. 49.100 /  3. 49.100
   libswscale      2.  2.100 /  2.  2.100
   libswresample   0. 17.102 /  0. 17.102
   libpostproc    52.  2.100 / 52.  2.100
Input #0, matroska,webm, from 'Amis Raynaut-mUTtmdb4TCs.f171.webm':
   Duration: 00:04:00.73, start: 0.000000, bitrate: 118 kb/s
     Stream #0:0(eng): Audio: vorbis, 44100 Hz, stereo, fltp (default)
Input #1, matroska,webm, from 'Amis Raynaut-mUTtmdb4TCs.f248.webm':
   Duration: 00:04:00.50, start: 0.000000, bitrate: 583 kb/s
     Stream #1:0(eng): Video: vp9, 1920x1080, SAR 1:1 DAR 16:9, 6 fps, 6 
tbr, 1k tbn, 1k tbc (default)
[buffer @ 0xb414da0] Unable to parse option value "-1" as pixel format
Error opening filters!