Hi, I've recorded videos and not saved them, thought they were lost forever, but luckily I have an app called 'Dumpter' installed on my phone, a recycle bin for Android, found it in there. Recommend this app. Might be too late for your previous recording but a good safety feature. I've recovered photos I deleted by mistake as well, so well worth having.
You could try some file recovery software installed on a PC and see if you can find your missing video by connecting your phone or loading the SD card, worth a try.