Ben C. answered 03/26/19
I'm not familiar enough with your specific camera to know if it's a setting, but chances are you either pressed the shutter button while recording (which can usually take a photo during video) or they are periodic thumbnails being taken automatically with the video. Either way you should be able to safely delete them if you don't need them for any reason.
I would suggest taking a couple test videos and making sure not to press any buttons to figure out for sure if it's a setting or you took them during the video recording.