Here's why:
* The kidnapper: The film features Hannibal Lecter, a brilliant but cannibalistic serial killer and psychiatrist.
* The girls: The main character, Clarice Starling, is an FBI trainee who seeks Lecter's help to catch another serial killer, "Buffalo Bill," who skins his victims.
* The basement: Buffalo Bill keeps his victims captive in his basement.
* The wedding dress: Buffalo Bill dresses his victims in a "skin suit" made from the skin of his previous victims. This can be interpreted as a macabre version of a wedding dress.
While the movie doesn't use a wedding dress to signal when he's about to kill, the use of the "skin suit" on his victims could be seen as a disturbing parallel to the wedding dress detail you mentioned.
It's important to note that the movie is very disturbing and deals with sensitive themes. If you are interested in watching it, be sure to research it beforehand and proceed with caution.