Having the same issue. It looks like the conclusion from this similar thread on the Unity forums is probably correct - it appears to be a RAM limit issue. I'm testing now to confirm. Unity stores StreamingAssets data as JAR files which must be fully loaded into RAM before they can be read by the app. If your file size maxes out the device's RAM, the video won't play. Solutions 1) split video into multiple vids 2) store video on the SD card instead via persistent data path - https://forum.unity3d.com/threads/large-videos-not-playing-on-gear-vr-but-do-play-on-google-cardboard-any-ideas.395779/
