$ ffmpeg -i Spiel\ mit.swf -c:v copy -an Spiel5.mkv
ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jun  9 2012 15:43:10 with llvm_gcc 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.9.00)
  configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --arch=x86_64 --enable-runtime-cpudetect
  libavutil      51. 54.100 / 51. 54.100
  libavcodec     54. 23.100 / 54. 23.100
  libavformat    54.  6.100 / 54.  6.100
  libavdevice    54.  0.100 / 54.  0.100
  libavfilter     2. 77.100 /  2. 77.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
[swf @ 0x7fa81a006600] max_analyze_duration 5000000 reached at 5000000
[swf @ 0x7fa81a006600] Estimating duration from bitrate, this may be inaccurate
Input #0, swf, from 'Spiel mit.swf':
  Duration: 00:27:32.64, start: 0.000000, bitrate: 127 kb/s
    Stream #0:0: Video: flv1, yuv420p, 480x352, 25 fps, 25 tbr, 25 tbn
    Stream #0:1: Audio: mp3, 44100 Hz, stereo, s16, 128 kb/s
Output #0, matroska, to 'Spiel5.mkv':
  Metadata:
    encoder         : Lavf54.6.100
    Stream #0:0: Video: flv1 (FLV1 / 0x31564C46), yuv420p, 480x352, q=2-31, 25 fps, 1k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=    0 fps=0.0 q=-1.0 Lsize=       1kB time=00:00:00.00 bitrate=   0.0kbits/s
video:0kB audio:0kB global headers:0kB muxing overhead inf%
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)