The Filename - Tag dialog displays a sample source filename but it would be good it to include also some path e.g. the path segment specified by the format string. And also good would be for this item to be not next to the "Format string:" label (where it is confusing), but below the format string control, at the top of the mini-preview list e.g.

Format string:

| \%album%\%track% %title% !

(path ...\Greatest Hits\01 My Way.mp3)
album Greatest Hits
track 01
title My Way