$ ffmpeg -y -i finale.flv -vcodec copy -acodec copy -atag spex finale2.flv
FFmpeg version git-48a0602, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --enable-gpl --enable-nonfree --enable-libx264 --enable-libtheora --enable-libxvid --enable-libdc1394 --enable-postproc --enable-avfilter --enable-libmp3lame --enable-libfaad --enable-libfaac --enable-pthreads --enable-ffplay --enable-ffserver --disable-shared --disable-debug --extra-ldflags=-static
  libavutil     50. 3. 0 / 50. 3. 0
  libavcodec    52.29. 0 / 52.29. 0
  libavformat   52.32. 0 / 52.32. 0
  libavdevice   52. 2. 0 / 52. 2. 0
  libavfilter    0. 5. 0 /  0. 5. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on May 19 2009 12:57:18, gcc: 4.3.3
[flv @ 0x9ddbae0]skipping flv packet: type 18, size 12395, flags 0

Seems stream 0 codec frame rate differs from container frame rate: 2000.00 (2000/1) -> 29.97 (30000/1001)
Input #0, flv, from 'finale.flv':
  Duration: 01:39:04.24, start: 0.000000, bitrate: N/A
    Stream #0.0: Video: h264, yuv420p, 1280x720, 29.97 tbr, 1k tbn, 2k tbc
    Stream #0.1: Audio: 0x0000, 16000 Hz, mono, s16
[NULL @ 0x9de6db0]flv does not support that sample rate, choose from (44100, 22050, 11025).
Output #0, flv, to 'finale2.flv':
    Stream #0.0: Video: libx264, yuv420p, 1280x720, q=2-31, 1k tbn, 1k tbc
    Stream #0.1: Audio: spex / 0x78657073, 16000 Hz, mono, s16
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Could not write header for output file #0 (incorrect codec parameters ?)