Search and Replace text to another

hi,
(sorry for bad english)
I would like to replace text in multiple posts. I try Search & Replace plugin but It works with a specific text.
eg:
i would remove from txt links all without filename:
http://domain.com/a_string_of_letters/filename
like in Total Commander
http://domain.com/????????????

but I not found plugin that do this.
all plugins which i found replace unequivocal text to another.

maybe directly on database? but i dont know how