D:\ffmpeg>ffmpeg.exe -i output.mp4 -timestamp now test2.mp4
ffmpeg version N-61663-g19139d8 Copyright (c) 2000-2014 the FFmpeg developers
  built on Mar 20 2014 22:06:17 with gcc 4.8.2 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetyp
e --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --ena
ble-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-l
ibopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libsp
eex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aa
cenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavp
ack --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable
-zlib
  libavutil      52. 67.100 / 52. 67.100
  libavcodec     55. 52.102 / 55. 52.102
  libavformat    55. 34.101 / 55. 34.101
  libavdevice    55. 11.100 / 55. 11.100
  libavfilter     4.  3.100 /  4.  3.100
  libswscale      2.  5.102 /  2.  5.102
  libswresample   0. 18.100 /  0. 18.100
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf55.34.101
  Duration: 00:01:56.03, start: 0.023220, bitrate: 12137 kb/s
    Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yu
v420p, 1920x1080, 12134 kb/s, 30.33 fps, 30.33 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      rotate          : 180
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 1 kb
/s (default)
    Metadata:
      handler_name    : SoundHandler
Option timestamp (set the recording timestamp ('now' to set the current time)) c
annot be applied to output file test2.mp4 -- you are trying to apply an input op
tion to an output file or vice versa. Move this option before the file it belong
s to.
Error parsing options for output file test2.mp4.
Error opening output files: Error number -22 occurred

D:\ffmpeg>