Videos having higher resolutions (e.g. 2k or 4k) are not playable on low end and mid range devices sometimes. Even most of the iOS devices supports maximum 1080p resolution video playback natively. Due to such limitations, user may see black screen when viewing high resolution videos (e.g 3840x2160) in InstaVR generated apps. To fix this issue, InstaVR provides provision to scale down your video resolution to 1920 x 1080 (HD) to be played back on your devices.
Please set below setting in InstaVR Dashboard prior to packaging apps :
Package --> iOS --> Advanced --> Video Resolution