Silence ffmpeg warning on video seek.
Silence ffmpeg warning on video seek.

svn path=/trunk/libavg/; revision=2038

yyd01245/libavg,scotty007/libavg,hoodie/libavg,th3infinity/libavg,yyd01245/libavg,scotty007/libavg,hoodie/libavg,libavg/libavg,hoodie/libavg,libavg/libavg,scotty007/libavg,th3infinity/libavg,th3infinity/libavg,th3infinity/libavg,yyd01245/libavg,libavg/libavg,yyd01245/libavg,scotty007/libavg,libavg/libavg,hoodie/libavg