Excellent, but it's currently broken Rated 4 out of 5 stars

As of December 20, year 2012, the latest version of Download Helper is not working on YouTube correctly, nor does it work correctly with a newer version of Firefox (18.0).

This review is for a previous version of the add-on (4.9.12.1-signed). 

It looks ok to me. Can you provide details to bugzilla.downloadhelper.net ?