It looks like camera-ui2 got closed/crashed before saving of video file ended.

I've seen similar results once, when I recorded ~2 hours long concert - after stopping recording, camera-ui2 got frozen for ages (using 99% CPU), so after 30 minutes, I killed it. The result was video with screwed container - everything was saved in practice, but wrapping it into mp4 failed. I had to use mp4 video recovering tools (and even then, it wasn't possible to restore video with 100% correct framerate & co - despite fact, that technically, all frames were saved to disc. Yes, mp4 sucks.)

Summing it up - it seems to me, that camera-ui2 sometimes get stuck, and won't finish saving video properly, no matter how long time you'll give it, to do so. Probably, it can happen for both short and long recordings (but long ones have higher probability - warning, my subjective conclusion, not based on any real research).

/Estel