$ ffmpeg -vcodec copy -acodec copy -scodec xsub -i Christmas\ 2010.avi -i Christmas\ 2010.sub -slang eng Christmas\ 2010\ subbed.avi
ffmpeg version N-35681-g16abd68, Copyright (c) 2000-2011 the FFmpeg developers
  built on Dec 11 2011 22:07:32 with gcc 4.6.2 20111125 (prerelease)
  configuration: --prefix=/usr --enable-libmp3lame --enable-libvorbis --enable-libxvid --enable-libx264 --enable-libvpx --enable-libtheora --enable-libgsm --enable-libspeex --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-librtmp --enable-libpulse --enable-gpl --enable-version3 --enable-runtime-cpudetect --disable-debug --disable-static
  libavutil    51. 32. 0 / 51. 32. 0
  libavcodec   53. 42. 0 / 53. 42. 0
  libavformat  53. 24. 0 / 53. 24. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 53. 0 /  2. 53. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0
Unknown decoder 'copy'
$ sudo pacman -U /var/cache/pacman/pkg/ffmpeg-20111003-1-i686.pkg.tar.xz /var/cache/pacman/pkg/x264-20111001-1-i686.pkg.tar.xz
resolving dependencies...
looking for inter-conflicts...

Targets (2): x264-20111001-1 [0.35 MB]  ffmpeg-20111003-1 [4.22 MB]

Total Download Size:    0.00 MB
Total Installed Size:   20.90 MB

Proceed with installation? [Y/n] 
(2/2) checking package integrity                   [----------------------] 100%
(2/2) checking for file conflicts                  [----------------------] 100%
(1/2) upgrading x264                               [----------------------] 100%
(2/2) upgrading ffmpeg                             [----------------------] 100%
$ ffmpeg -vcodec copy -acodec copy -scodec xsub -i Christmas\ 2010.avi -i Christmas\ 2010.sub -slang eng Christmas\ 2010\ subbed.avi
ffmpeg version 0.7.6, Copyright (c) 2000-2011 the FFmpeg developers
  built on Oct  3 2011 13:06:32 with gcc 4.6.1 20110819 (prerelease)
  configuration: --prefix=/usr --enable-libmp3lame --enable-libvorbis --enable-libxvid --enable-libx264 --enable-libvpx --enable-libtheora --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-librtmp --enable-gpl --enable-version3 --enable-runtime-cpudetect --disable-debug
  libavutil    50. 43. 0 / 50. 43. 0
  libavcodec   52.122. 0 / 52.122. 0
  libavformat  52.110. 0 / 52.110. 0
  libavdevice  52.  5. 0 / 52.  5. 0
  libavfilter   1. 80. 0 /  1. 80. 0
  libswscale    0. 14. 1 /  0. 14. 1
  libpostproc  51.  2. 0 / 51.  2. 0
Input #0, avi, from 'Christmas 2010.avi':
  Metadata:
    encoder         : transcode-1.1.7
  Duration: 00:45:04.30, start: 0.000000, bitrate: 4026 kb/s
    Stream #0.0: Video: mpeg4, yuv420p, 720x480 [PAR 59:50 DAR 177:100], 29.97 tbr, 29.97 tbn, 29.97 tbc
    Stream #0.1: Audio: mp3, 48000 Hz, stereo, s16, 192 kb/s
    Stream #0.2: Audio: mp3, 48000 Hz, stereo, s16, 192 kb/s
Input #1, mpeg, from 'Christmas 2010.sub':
  Duration: 00:45:01.02, start: 2.783122, bitrate: 6 kb/s
    Stream #1.0[0x20]: Subtitle: dvdsub
Output #0, avi, to 'Christmas 2011 subbed.avi':
  Metadata:
    ISFT            : Lavf52.110.0
    Stream #0.0: Video: mpeg4, yuv420p, 720x480 [PAR 59:50 DAR 177:100], q=2-31, 29.97 tbn, 29.97 tbc
    Stream #0.1: Audio: libmp3lame, 48000 Hz, stereo, 192 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Press [q] to stop, [?] for helpframe= 9771 fps=5847 q=-1.0 Lsize=  104015kB time=00:05:26.01 bitrate=2613.7kbits/s    
video:95812kB audio:7641kB global headers:0kB muxing overhead 0.543256%
Received signal 2: terminating.
$