Took me a moment to figure out that I had to type in a search string at the top (from your description I first thought it would just return a list of all files in the directory I specified, which would, of course, have been rather pointless), and another moment to figure out that I had to specify the exact filename, including file extension, or it wouldn’t find anything (tried with * and % as wildcards, which yielded no results). Of course, this is less relevant if you’ll always be receiving file names as comma-separated values from a database dump or something similar.
Other than that, it seemed to work like what you described.
Screenshots:
Just opened app
Search yielded 0 results (note: “metamorf” is the name of a folder, so apparently it only finds files, not folders—not sure if this is intended or not)
Search that actually yielded a result (I tried thinking of something that would give perhaps five or six results, but only managed to find either one result or 50, which would have made the screenshot too big)
