The plugin adds this by default:
Breadcrumb, generated by Breadcrumb NavXT 2.1.4 - http://mtekk.weblogs.us/code
In my opinion it's over the top. While it's a comment, it is spurious code. It marginally increases the size of the page and doesn't serve any useful purpose.
I have disabled this by commenting out line 665 in the breadcrumb_navxt_class.php file (plugin version 2.1.4).
As a plugin author myself, I think this type of credit is over the top.
Cheers - Callum.