Dash cams record on loops and you can usually change the video lengths. Mine has a button you can easily press to mark that video (and the one before/after if less than 1 minute in/to go) which moves that video to a different folder and prevents it being overwritten. It also does that automatically if it senses a crash. If you have a large enough SD card you won’t have to transfer it anywhere for quite a while depending on how much you want to save. I go a few months of saving the odd thing before moving them over to my laptop