Can't find 100gb of movie files on my macbook
If you know the name of one of the movies (files) that you are looking for or if you know what format the movie is in (extension) then you should be able to use Spotlight search

My favorite way to bring it up is hit Command-Space and you will see a search bar in the middle of your screen (Yosemite)

Start typing the name or file extension and if it exists, you will start seeing search results pop up.

Select any of the files and hit Command-I for Get Info and you should see a window like this pop up:



Under the "General" tab, you will see a field labeled "Where".  This is the path to your file where it's located.  In this example, the location is /Applications.

You can now use Finder to "Go to that folder".  Hit Shift-Command-G and type that location into the dialog box.  A Finder window will open, at that location.  Your file(s) will be there.

As for names - well, you will be the one who knows what they are.  As for the extensions, there are many, but some of the most common are .MP4, MPEG, and MOV.  for a complete list, check out Video File Extensions