Add hidden movies back into library without downloading

I've purchased hundreds of movies. Months ago I decided to hide many of them but keep the files on my hard drive; that option was offered. Now I have unhidden those titles. On a hunch I right-clicked on one of them, and "download" was the only option. There doesn't seem to be a way to reconnect the titles with the files already on my computer

I don't want to re-download everything unnecessarily and use up my monthly data allowance! If I can't just use the files on my hard drive, why was that option offered when I hid the titles in the first place?

To clarify, I want to play these movies on the computer where they are stored, not on a mobile device or the AppleTV box.