This extension was fine until Firefox version 70.0 where it soesn't show the download progress bar.
Previously I would have given 4 or 5 stars but to me the bug which prevents the download bar appearing makes it no more useful than the built in download manager. I really hope a fix comes soon.

UPDATE.

Now installed Firefox version 70.0 RC2 and DM (S3) is now working correctly again. Now worth 5 stars again.