Large Files & Drop Box

When I am looking at my 'Large Files' I see that I have several that are QuickTime movies or MPeg-4 movie files among others that are also saved in my Dropbox. I have my Dropbox Smart Sync set up to reduce the files I have for quick access on my computer. So they are NOT saved anywhere on my hard drive and are only supposed to be accessible if I open DropBox in my browser.

I double check all these files that say they are on my Mac, and they are not synced in my Dropbox. So what I would love to know is:

1. Why are they showing up in my large files when they are not supposed to be there and I checked to ensure they were not synced via Dropbox?
2. Can I delete them here in the large files area and not have them delete in my Dropbox account?

Screen shot.