I just recently started using DXVA (Direct X Video Acceleration) to watch high definition media, and I can't recommend it highly enough. By using my video card to play h264 video, my cpu usage has been cut in half and I can playback files that had been too heavy a load on my cpu previously. If you have a decent video card, DXVA is the way to go. Period.
I'm sure many of you are aware of DXVA and are using it as we speak, but for others who would like to get the most out of your video card and cpu, here's the guide I used to help set things up.
Code:
http://imouto.my/watching-h264-videos-using-dxva/
You can completely skip step 7 as this pertains mainly to anime freaks who watch media with weird subtitles. And I'm not sure if it's absolutely necessary to block ffdshow video filter in step 6 because DXVA is working fine for me without blocking it (blocking it will screw with AVI playback)... mess around and see what works for you, I suppose.
**For those who don't have a compatible video card, you might want to look into CoreAVC 2.0, which is one of the better and faster decoders out there in terms of CPU usage. You have to pay to use it, however. Here is an older version that's free to use though.
Code:
http://www.megaupload.com/?d=0OW7YGDJ
Hope this helps some of you to enjoy watching stuff with DXVA as much as I do.