I have an iMac running OS X 10.9.2. The problem I'm having is that my hard drive is full - mostly due to HD home videos that I have saved to iMovie. I need to move them to an external hard drive in order to free up some room. I really would like to put them (2 copies of the same videos) on 2 separate hard drives, so that I will have a back-up in case one fails. I am not really that mac savvy - so I was wondering if someone could tell me the best/easiest way to go about doing this. Where I get hung up is if I move it to one drive, then it's no longer on the mac - so how do I put a copy on a second drive? Any help/suggestions would be greatly appreciated!! Thanks!