This is a great extension. One of my biggest gripe switching from Chrome to Firefox was how terrible Firefox's built in translator was, where it couldn't auto detect languages, could only translate one language at a time, and even then the translation was terrible. Especially on Youtube where the comment section has multiple languages. This extension eliminated that issue for me.

The extension was a bit confusing at first since you have to copy and paste the permission script in the options, and it comes with a bunch of redundant options enable by default which are nice to have but add a bunch of clutter to the menus and confusion to new users.

If you just wanted a simply Chrome like translation feature in Firefox like I did, just disable all the other options in the various UI menus, except for.

Insert Google Translate Element in page

Switch between translation and source text

Show / hide toolbar of Google Translate Element

With just those 3 options enable you basically have identical functionality to Chrome's default translator which works on most sites. Though oddly enough the "Insert Google Translate Element in page" doesn't work on any of the Mozilla webpages, like this review section, where the option is greyed out.