No duration for flv video

[AmshTemp]

ffplay.exe can't seek on this flash video:
​http://ia700809.us.archive.org/34/items/MaharatJam3Alma3lomat-dr.khaled/MaharatJam3Alma3lomat-dr.khaled.flv

ffplay uncut console output when seeking with my mouse:
C:\>ffplay -v 9 -loglevel 99 -i MaharatJam3Alma3lomat-dr.khaled.flv
ffplay version N-37541-g670229e Copyright (c) 2003-2012 the FFmpeg developers

built on Feb 3 2012 20:07:47 with gcc 4.6.2
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-runtime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
libavutil 51. 37.100 / 51. 37.100
libavcodec 54. 0.102 / 54. 0.102
libavformat 54. 0.100 / 54. 0.100
libavdevice 53. 4.100 / 53. 4.100
libavfilter 2. 61.100 / 2. 61.100
libswscale 2. 1.100 / 2. 1.100
libswresample 0. 6.100 / 0. 6.100
libpostproc 52. 0.100 / 52. 0.100

[flv @ 0033EBC0] Format flv probed with size=2048 and score=100
[flv @ 0033EBC0] All info found
Input #0, flv, from 'MaharatJam3Alma3lomat-dr.khaled.flv':

Duration: 00:00:00.00, start: 0.000000, bitrate: -2147483 kb/s

Stream #0:0, 41, 1/1000: Video: h264 (Baseline), yuv420p, 480x360 [SAR 1:1 DAR 4:3], 1/60, 25 tbr, 1k tbn, 60 tbc
Stream #0:1, 81, 1/1000: Audio: mp3, 44100 Hz, stereo, s16, 96 kb/s

[h264 @ 0033FAA0] detected 1 logical cores
[flv @ 0033EBC0] skipping flv packet: type 142, size 6225565, flags 0=0/0
[flv @ 0033EBC0] skipping flv packet: type 215, size 14137226, flags 0
[flv @ 0033EBC0] skipping flv packet: type 97, size 1005211, flags 0
[flv @ 0033EBC0] skipping flv packet: type 230, size 15913907, flags 0
[flv @ 0033EBC0] skipping flv packet: type 0, size 155939, flags 0
[flv @ 0033EBC0] skipping flv packet: type 187, size 4683771, flags 0
[flv @ 0033EBC0] skipping flv packet: type 53, size 3099169, flags 0
[flv @ 0033EBC0] skipping flv packet: type 90, size 12540563, flags 0
[flv @ 0033EBC0] skipping flv packet: type 29, size 5607130, flags 0
[flv @ 0033EBC0] skipping flv packet: type 17, size 4027269, flags 0
[flv @ 0033EBC0] skipping flv packet: type 36, size 7248825, flags 0
[flv @ 0033EBC0] skipping flv packet: type 221, size 15632287, flags 0
[flv @ 0033EBC0] skipping flv packet: type 205, size 15214600, flags 0
[flv @ 0033EBC0] skipping flv packet: type 14, size 13097822, flags 0
[flv @ 0033EBC0] skipping flv packet: type 172, size 15245894, flags 0
[flv @ 0033EBC0] skipping flv packet: type 215, size 10641055, flags 0
[flv @ 0033EBC0] skipping flv packet: type 253, size 9035749, flags 0
[flv @ 0033EBC0] skipping flv packet: type 0, size 12287, flags 0
[flv @ 0033EBC0] skipping flv packet: type 180, size 8691561, flags 0
[flv @ 0033EBC0] skipping flv packet: type 170, size 8881523, flags 0
[flv @ 0033EBC0] skipping flv packet: type 74, size 11166274, flags 0

20.03 A-V: -0.018 fd= 1 aq= 0KB vq= 0KB sq= 0B f=0/0

[Carl Eugen Hoyos]

Seeking with Page up/down, up/down and left/right works fine, mouse seeking fails because the duration is unknown.