I have on old MacMini that cannot support updates for Firefox, but I made the mistake of downloading 48.0.2 when it was offered today. 6.3.1 Released Works with Firefox 36.0 - 56.* Version 2.6.0 Released Dec. I'm guessing you mean Video DownloadHelper. On the extension page on scroll down to where it says Version Information and click on it to see a 'See complete version history' link.
