Short version is "an MPEG2 codec of sorts". A few years ago, free options were rare but now they are commonplace. You can get ffdshow to do MPEG2 and then you can play DVDs in almost any standard playerI'm not sure what you mean by dvd decoder
Perhaps this was back in Windows2000 days? My early W2K days, System32\dvdplay.exe could play it fine (or it might have been WME, it's all a blur at this age)Oddly enough I got ffdshow a while back and WMP still couldn't play DVDs, yet I clearly remember using it for WMP before. So I'm using my 30 days of purevideo right now.