An automated installer script I maintain invoked the command:
That should have failed, because the package maintainer had inadvertently misnamed the file, (as binutils-2.19.1-mingw32-src.tar.gz). However, the download succeeded, retrieving not the file requested, but the raw HTML for the MinGW Project 'files' page, saving it to a local file called 'showfiles.php?group_id=2435'.
Manually invoking the same wget command, from an interactive shell, produces the attached transcript.
This behaviour is so bizarre that it surely cannot be intended; it certainly isn't remotely useful. I've modified my scripts, to detect the falsely successful download, but it would be more useful if your download service would simply say "no such file", and cause wget to fail.