Large avi not playing to the end
It is hard to say without seeing the file itself, but my best guess is that an issue occurred causing the data stream to die but the meta data was still set "properly".  Generally, the actual video data itself is not looked at for the length of the video.  Instead, there is header meta data in the file that holds the video stream which indicates how long the video is and how it is encoded.  It is possible that the video stream either had an error at around 9 minutes or perhaps it simply stopped recording around that time, however the timer kept going and the meta data for the length wasn't written until the end.

This would also explain why it goes dark, because the video stream player would try to play it, but the content isn't there, so it has nothing to play.

If the file just has a corruption for a short while and then works again, you might be able to get around it by splitting the video stream in to multiple parts, but my guess is that the data was probably not encoded in the first place and your stream itself is probably truncated.