DLNA network video streaming, including support for formats such as .mkv, will begin rolling out to Xbox One next month.
A new app will enable streaming from USB and, at an unspecified later date, networked media server devices. More or less every video format available will be supported.
There are a number of other functionality additions planned too, such as a revamped Friends section, an expanded Snap Centre with support for messaging and achievements, threaded messaging (including DVR clips), TV streaming to SmartGlass, a new Live TV Mini Guide that sticks at the bottom of the screen and the ability to have consoles boot straight into TV mode.
The rollout will be staggered, as per previous updates.
Full details can be found at Major Nelson.