Sounds like you are. The provided example was done as I described in the forum posting.
The URL downloader will create an icon and it will not look like a .mbz backup, but rather like this:
http: / / moodle.tcea.org/moodle2/moodle/local/hub/webservice/download.php?courseid=1&filetype=backup&remotemoodleurl= http %3A%2F%2Fmoodle.tcea.org%2Fmoodle2%2Fmoodle
I put some extra spaces in the above so as to attempt in rendering it non-clickable here.
Once the file is linked in your URL downloader chooser, you have to click it again during the restore. That's when the link turns into a .mbz. At least it did for me.
'spirit of sharing', Ken