When I was still on Windows XP, I used ffdshow to take care of all my video and audio codecs needs (with fully customizable subtitles). I did not need any other video player except Windows Media Player.
Is there an ffdshow equivalent for the Mac? The objective is the same: that I shouldn't have to install any other video player, not even VLC, or the trial-bloatware-ridden DivX. I'm on Snow Leopard.