I had a bunch of photos on my SD card (Sony alpha 6000) and then shot some videos using the timelapse app. I could see them when in playback mode on the LCD. Now (3 days later, not using the camera meanwhile, but I did change batteries), I don't see the videos on the SD card! Where did they go?  Is it possible that the timelapse application didn't save them to SD card and they're gone because I swapped batteries??

Hi, No, swapped batteries is not responsible for video deleted/lost. May be there is the chance your SD card infected due to virus or malware when you play video on your LCD. There are many ways to restore the file from SD card, you can use video recovery software such as Stellar Photo Recovery which help you to get deleted videos, photos, audio files from your SD card.  Thanks!

Thanks. I've solved it meanwhile - turns out the timelapse app stores the videos on a separate subfolder within the SD card, not with the rest of the images/videos, and I saw them before because I was seeing them from within the app - the camera itself doesn't see them after you leave the app.