User blog comment:DaNASCAT/Technical Update: March 20, 2012/@comment-1513877-20120324033637/@comment-3441771-20120327035057

This is a guess: The -moz- are there because people (programers) seem to still think that FF 3.6 (and earlier) is still around. I have been guilty of coding with -moz-. It may well be that FF still recognizes -moz- as a code. And does act on it. If I get time: I'll test it... :)