This is, to my knowledge the first public testing build with FFMPEG support for windows. FFMPEG is a i/o library for multimedia content. It let you open a various range of file in sequencer for example and give you the chance to output to various know format such as mpeg,DV,AVI,quicktime and let you multiplex audio and video at render time.
Needless to say for sequencer work this build kick ass.
Warning: I've been forced to use this build in production env. You should not consider tring it unless you are about to commit suicide. The sequencer is very unstable. Although it is feasible. I save after every move. I noticed: It seam to crash on end of audio strip at playback, Shift-D a stip with effect applied can be dangerous, applying meta on DV strip can give black render, meta on meta can give segfault...
Now you know ^_^
Go give this build a good test drive.
And please report repeatable Crash in the bug tracker! this thing must be stable for release

For curious this build is a mingw one. GCC for windows. It is supposed to be much faster than cygwin but a bit slower than msvc.
http://www.graphicall.org/builds/builds ... how&id=132