It does support DXVA out of the box and the same does Media Player Classic ( official site download) and it also supports DXVA out of the box actually. The most modern player as for me it is PotPlayer ( official site download). I believe nobody is using windows XP right now but anyway there are always some paranoiacs or old-schoolers who using Windows XP (especially in Russia). But the problem here is that not all operating systems support it (Windows XP does not, but since Windows 7 it’s ok). It is a technology used for acceleration of video decoding using discrete video card or integrated gpu core in CPU (Intel HD core i5, core i7 and etc). So if you already downloaded some good content in HEVC but having issues on how to watch HEVC on old hardware on your computer or laptop just head to the bottom of this post (there are some images and tutorials). So the whole world is already prepared for H264 codec (which is also known an AVC) but not every hardware supports H265 (HEVC) which should be better version of H264.

Hevc codec for windows 7