Should not be possible to record a video with zero seconds duration

At the moment the camera allows us to record videos that basically have no content (i.e. zero length duration).
To do this simply tap the record button and immediately tap it again to stop recording.

When you swipe to the photo roll to review the video, a "broken" thumbnail image appears (looking like a video reel frame) because the thumbnailer is failing to extract any frames from it (because probably there are no frames in the video).

Ideally we should either require a minimum length before we allow stopping the recording, or discard videos that are too short.