Good news,
a new version of the Win8.1 app has been released today.

This is mostly a bugfix/maintenance version, but we managed to squeeze some goodies in there as well.
It includes the following:


Connectivity
Lots of changes to Media Browser Connect, the connection should now be a lot more stable and faster

Added Next Up in TV Show details view

Continuing on a Series is now easier than ever, just select the show of your choice and the next up episode is there.

Better support for smaller screens (7")
We made some tweaks to make sure the app looks just as good even on smaller screens.

Playback
New transcoding profiles and the option to turn HLS off (Settings -> Streaming -> Use Alternative Transcoding)
If you have a problem playing some video files, you can try this.
Better Direct Stream support for Mp4
Direct Stream support for M4A

Other changes
Screensaver (Starts after 60 seconds)
Improved Picture Quality on thumbnails
Removed Light Theme
Bug fix for artist details view in portrait mode
Lots of minor UI tweaks.
Live Tile fix

Get it now: https://apps.microsoft.com/windows/app/media-browser/ad55a2f0-9897-47bd-8944-bed3aefd5d06