I don't have much space on my C drive. 

I was surprised to see why my C drive space was getting less and less, even though I saved my movie maker .mp4's in an external hard drive. So I did some digging and found V3tapps .mp4 files of the same footage, right there on my C drive in Videos\HD Movie Maker\Data 

1. Is it safe to remove those files? Will it somehow compromise my .mp4 savefiles in the external hard-drive?

2. Is there a way to turn off the creation of these files?

I really don't need doubles of footage cluttering my C drive, nor the trouble of having to manually remove them every time.