Maybe I'm misunderstanding something. Yes, if I search for .tif as you suggest, it finds all of them in all indexed areas. The problem is that I have a bunch of .tifs that I don't want to delete, that are for a different purpose in a different program.
I attempted to select the desired directory after the search completed, but it then showed all files in the folder, regardless of the extension. I guess using the search function would reduce the amount of tedium selecting files, but it still isn't as simple as I would desire.