I removed some word in the command line, I'm a bit further now.. it's saying that there is an error in mencoder libformat.

Code:
/usr/local/bin/mencoder '/home/admin/domains/degroenehel.tv/public_html/video/24082007127.mp4' -o /home/admin/domains/degroenehel.tv/public_html/flvideo/1187994234137797706.flv -of lavf -oac mp3lame -lameopts abr:br=56 -ovc lavc -lavcopts vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 

MEncoder dev-SVN-r24142-3.4.6 (C) 2000-2007 MPlayer Team
CPU: Intel(R) Celeron(R) CPU 3.06GHz (Family: 15, Model: 4, Stepping: 9)
CPUflags: Type: 15 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2

success: format: 0  data: 0x0 - 0x50c47
ISO: File Type Major Brand: ISO/IEC 14496-1 (MPEG-4 system) v2
Quicktime/MOV file format detected.
[mov] Video stream found, -vid 0
[mov] Audio stream found, -aid 1
VIDEO:  [mp4v]  320x240  24bpp  15.298 fps    0.0 kbps ( 0.0 kbyte/s)
[V] filefmt:7  fourcc:0x7634706D  size:320x240  fps:15.30  ftime:=0.0654
==========================================================================
Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)
AUDIO: 32000 Hz, 2 ch, s16le, 48.2 kbit/4.71% (ratio: 6025->128000)
Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio) decoder)
==========================================================================
** MUXER_LAVF *****************************************************************
REMEMBER: MEncoder's libavformat muxing is presently broken and can generate
INCORRECT files in the presence of B frames. Moreover, due to bugs MPlayer
will play these INCORRECT files as if nothing were wrong!
*******************************************************************************
OK, exit
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffodivx] vfm: ffmpeg (FFmpeg MPEG-4)
==========================================================================
MP3 audio selected.
VDec: vo config request - 320 x 240 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
videocodec: libavcodec (320x240 fourcc=31564c46 [FLV1])
[VE_LAVC] High quality encoding selected (non-realtime)!
Compiler did not align stack variables. Libavcodec has been miscompiled
and may be very slow or crash. This is not a bug in libavcodec,
but in the compiler. You may try recompiling using gcc >= 4.2.
Do not report crashes to FFmpeg developers.
VIDEO CODEC ID: 22
AUDIO CODEC ID: 15001, TAG: 0
Writing header...
[NULL @ 0x8669a10]flv does not support that sample rate, choose from (44100, 22050, 11025).
Floating point exception