Added include compiler switches for windows to make pthread.h accessible
and reverted Joshua's patch.
(Joshua: the prefetch buffering has _nothing_ to do with FFMPEG!)
If this still does not fix the problem, please send an email to me!
I also fixed
source\blender\src\sequence.c(1405) : error C2275: 'PrefetchThread'
GCC is way to gracefully in latest versions... :)