I got smooth streaming working... that was an adventure but it works nicely with Azure Media Services. However what's not so nice is the blurry video at first because it's fast playing without caching enough to use a higher quality stream. Using the AMP video player for azure on web you can set the heuristicProfile flag to "High Quality" and voilà it buffers more and uses the higher quality stream.
How does one set the heuristic profile on UWP Video playback with smooth streaming so that it will choose the highest quality resolution that will work with the current connection so that video looks good right from the start of playback?
Have you tried to use the Select Track method to select the highest bitrate on startup and then after start unselect that track to allow it to adapt naturally?
See this sample: https://code.msdn.microsoft.com/windowsapps/A-Windows-8-Smooth-883c3b44