A sidecar .json file is required to view 360 videos in VR Player v2.5 for Windows, macOS and Android Cardboard. Otherwise, the video will play back in virtual cinema (2D) mode.
The .json file is a simple text file containing the following:
A template is attached to this message. Download it and copy/rename at will rather than create your own from scratch.
The .json file must bear the same name as the video file it supports, and be located in the same folder.