Rated 5 out of 5 stars

Firefox 4 workaround:
- Right-click and download file on "Add to firefox" button.
- Open xpi file in your favorite archiver software
- Edit the install.rdf file and change the parameter for "maxVersion" to 4.0.
- save file in archive an drag-drop the .xpi file into the browser.
- Install

This review is for a previous version of the add-on (