Missing video and abnormally numbered videos when I get back from shooting

I have flown my first couple of missions and when I get home one or more of the videos that I took is missing. I know it is recording because I am watching it while it records. In addition, the videos are numbered backwards-the first video is missing, the second that I recorded is labeled DJI-0002, and the third one I took is labeled DJI-0001. Help would be appreciated!