The video might have been deleted because of program's error or a bug in the code. However, to recover it you will need to use a recovery application. For this operation, I recommend using Recuva. Recuva is a free application that has the possibility to recover deleted files. Install the application then specify the path where the video was stored. Check the video scanning option and then start the scanning procedure. After completion, your recoverable files will have green spot next to them. Right click the file and save it to another partition and that's it.