kobraking I think it comes from the fisheye. Its like the video all goes towards the center. Its "pointy" at the bottom.
Are you using an old version of the app? Or I guess more specifically which headset are you using?
The "pointy" comment makes me think your headset just isn't displaying the fisheye properly, since this is exactly what the 190 degree scenes will look like when they're not properly displayed. Basically like some sort of weird "black hole" effect that will be on the bottom of the video, sort of puling the rest of the video into it.