What Happened? Rated 2 out of 5 stars

I'm really sad to give up this add-on. It has been so useful for so long. If I load it I can no longer switch videos in YouTube without a delay of 30 seconds to several minutes. Uninstalling it solves the problem instantly. The problem is consistent. Where can I download an older version or does anyone know of a fix?
It's not fair for me to rate it as it was five stars and now it merits few.

This review is for a previous version of the add-on (4.6.5). 

Re: What Happened?

The problem is described here: http://bugzilla.downloadhelper.net/show_bug.cgi?id=5 and is due to your firewall not to DownloadHelper. You will find some workarounds in the bug description.