Update FFmpeg to latest stable release of 1.2

FFmpeg 1.2.5 "Magic"
1.2.5 was released on 2014-01-16. It is the latest stable FFmpeg release from the 1.2 release branch, which was cut from master on 2013-03-07. Amongst lots of other changes, it includes all changes from ffmpeg-mt, libav master of 2013-03-07, libav 9 as of 2013-03-07.

It includes the following library versions:
  libavutil      52. 18.100
  libavcodec     54. 92.100
  libavformat    54. 63.104
  libavdevice    54.  3.103
  libavfilter     3. 42.103
  libswscale      2.  2.100
  libswresample   0. 17.102
  libpostproc    52.  2.100