I did a search for this topic and three unrelated threads came up. So I want to Restore as new my MBA, but I want to first transfer (backup) all my MP4 files from Movie Folder to a Western Digital External Hard Drive (WDHD). I opened a New Finder Window and thought I could just Hi-light the file itself, hold down CMND and drag the file to the WDHD window, but it keeps giving me that "NO" Symbol (circle with diagonal line). I know this is simple, but can't figure it out. I tried to also COPY, but the Paste is grayed out. I also tried Cut, but won't allow me to paste. What's the deal? Thanks for any help any of you can provide me. Thanks. New to Mac (3months now), and I may still have Windows mindset.