But OP's video is just a video with very low frame rate (reported as 0.030 FPS from `mediainfo`). There is nothing broken about it.
Just become its file size is small, does not mean it can't be 15 hours long (one of the author is takeaway is "[t]he size of a video file is not an proper indicator for how long it is": but even without this hack, you can't do that either, since video can have whatever bitrates.)
Just become its file size is small, does not mean it can't be 15 hours long (one of the author is takeaway is "[t]he size of a video file is not an proper indicator for how long it is": but even without this hack, you can't do that either, since video can have whatever bitrates.)