PotPlayer can play them, either in side-by-side 2D (can't figure out how to remove the second image) or in 360 VR mode so you can zoom in/out and click to move your viewing position
The - and + key on D-pad will zoom in/out while in 360 VR mode (if not, check your key bindings in settings)
Open the file, go in full screen video mode, then at the bottom right of your screen click the 3D icon and then "Disable 3D Video Mode"
Then click the 360 icon at the bottom of the screen and click "Enable/Disable 360 Video Mode" and then Autoselect and finally untick "Display 4x90 camera angles"
To view in 2D mode simply disable 360 mode