Why are photos & videos mysteriously being removed upon low battery shut down?

[AC Question]

Last night, I took roughly ten 30 second videos and twenty photos on my Moto X (2nd Gen with internal memory only) running Android 5.1. Over the course of twenty minutes, I was taking video/pics and reviewing them from my gallery. While doing so, I battery died and the phone shut down. When I got the phone back on the charger and turned it back on, all of the video and photos I took were gone from my gallery. Any thoughts on how this could happen? Would it be possible that all that media over all that amount of time never wrote to the phone's disk and was sitting in memory? Any information you can give on how this happened or how to recover the files would be much appreciated!