My 'About This Mac' Storage is incorrect

When opening up my 'About This Mac' storage pane, it is telling me that my MacintoshHD has 50GB of 'Movie' Data. But I have searched everywhere on this hard drive for these files. Where are they? Why is it lying?

I recently had everything stored on my Macintosh HD - which ended up being 100% full and couldn't open anything so I bought an external hard drive. I have my time machine back ups stored on the EHD as well as most of my user data. I moved and/or deleted my movie files and somehow my internal HD thinks it's still carrying 50 GB of Movie data?