I transferred some videos from my Mac OS X Photos using iTunes app to my iPhone/iOS. I pressed Sync and it worked on transferring it to my iPhone. On my Mac OS X iTunes, the free storage for my iPhone reduced after the sync so I have some clue that transfer did happen. However, I don't where exactly in my iPhone are those videos transferred and how to access them?
The places to check would be:
- Photos app (Camera Roll)
- Movies/Videos app (if you're on iOS 9 or earlier; this app is gone in iOS 10)
- Cloud Photo Library