Needs work Rated 3 out of 5 stars
First of all, I didn't expect to find it in the Edit menu. I expected it to be in the tabbar's context menu (the most natural place IMO). Not finding it there, I checked Tools and File menus and the list of custom toolbar buttons. I only found it by simply going through every menu in FF.
Second, it ignores tab groups and copies URLs of all tabs you have open in the current window. This defeats its whole purpose for me personally. Well, at least it doesn't list tabs across all windows. IMO It would benefit from having options for both "current tab group only" and "all tabs in all windows". Maybe something more exotic like "current tab groups across all windows" as well.
Aside from all that, well, it works as advertized.