If you don't know that "Native MKV" support is, then you obviously haven't tried pirating videos off the internet. While the MKV fiel format is much more than just for pirating, it has always required certain players in order to play back this format. Thankfully, Windows 10 will now officially support this high-compression, high-quality video format. I'm sure that every Torrent user is a little happier with Windows 10 now.
If you want to test out support for MKV on your install, you can download a sample video from Jellyfish. After the file downloads, when you open it up, Windows will ask you what app you want to use to open this type of file with; select Windows Media Player. After you select WMP, a warning will pop up saying that the player does not support this file but if you click 'Yes', the file will then play without issues.