I use the USB stick that came with the car, which is sufficient, I don't need any more space than that.
I usually look over the clips saved while the car was in a parking lot while I was in a store or something. When it is snowing or raining it can easily produce 50 video clips sitting in my driveway overnight. Last weekend in my parent's garage it generated over 200 clips, no idea why. But even at 50 clips, I don't have time so sit there and sift through hundreds of videos and delete useless ones individually