Rated 4 out of 5 stars

OK, thanks for your reply, I see right clicking the video does indeed provide options. There is another issue that is effecting many addons now however, Firefox 4 recently changed cache behaviour so downloading from cache no longer works on NetVideo
http://forums.mozillazine.org/viewtopic.php?f=23&t=2098901

This review is for a previous version of the add-on (1.4).  This user has a previous review of this add-on.

You can right-click on youtube videos in the list and select which quality you like to download so there is no reason to detect the same video in each different quality. And by default the download button downloads in the best available quality even if you watch it in lower quality.