Rated 5 out of 5 stars

Home website is apparently death (several months).
I modded last version (5.6.14) to FFmaxVersion = 8.9
http://banashare.com/xsvukdzw62ph
Tested OK in FF6 stable, FF7 beta 2, and FF8 (aka. Aurora) alfa 2.
Thanks to passerby for finding the last version.

Guys, consider an alternative project with life as MAFF (also supports MHT).
https://addons.mozilla.org/en-EN/firefox/addon/mozilla-archive-format/

This review is for a previous version of the add-on (5.6.9).  This user has other reviews of this add-on.