Known Microsoft issue after last winter's Windows 10 Mobile update. When the phone is connected to an external monitor either by cable or through the dock, it will not playback video. Error message appears. A way to overcome this is by connecting speakers or a headset either to the phone or the dock. Then it will play video but once you disconnect the speakers/headset the problem returns. Long gone are the days of entering a meeting room and delivering fancy presentations with the phone alone. Microsoft made it possible and Microsoft ruined it. May I kindly ask if there is anyone in the community aware of a proper fix to the problem?