ffmpeg -i http://brightcove03-f.akamaihd.net/valgbodmandag1378107345_1_300k@80362 -vframes 1 -y frame.jpg

ffmpeg version N-54643-g15cee5e Copyright (c) 2000-2013 the FFmpeg developers
  built on Jul 11 2013 03:35:11 with gcc 4.7.3 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-g
tls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmodplug --e
ble-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger
-enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-l
vpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil      52. 39.100 / 52. 39.100
  libavcodec     55. 18.102 / 55. 18.102
  libavformat    55. 12.101 / 55. 12.101
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 80.100 /  3. 80.100
  libswscale      2.  3.100 /  2.  3.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100
[flv @ 00000000027da340] Stream discovered after head already parsed
Input #0, flv, from 'http://brightcove03-f.akamaihd.net/valgbodmandag1378107345_1_300k@80362':
  Metadata:
    encoder         : Lavf54.6.100
  Duration: 00:00:00.00, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: h264 (Constrained Baseline), yuv420p, 480x270 [SAR 1:1 DAR 16:9], 25 tbr, 1k tbn, 50 tbc
    Stream #0:1: Audio: aac, 44100 Hz, stereo, fltp, 128 kb/s
    Stream #0:2: Data: none
Output #0, image2, to 'frame.jpg':
  Metadata:
    encoder         : Lavf55.12.101
    Stream #0:0: Video: mjpeg, yuvj420p, 480x270 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> mjpeg)
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A
video:21kB audio:0kB subtitle:0 global headers:0kB muxing overhead -100.103238%