Video DownloadHelper beta program
Beta versions are development releases of the add-on that are pusblished more often, with new features and fixes. They are useful to validate code changes before it is published on the Firefox official add-ons site.
Once you install a beta version, you will automatically get beta updates in your browser. You can always switch back to public version by installing DownloadHelper latest stable release.
If you find problems with the beta version you are using, please report the issue with details in the support forum.
Starting on February 2018, Mozilla does no longer host beta versions of add-ons on the addons.mozilla.org web site, in favor of developer-hosted beta releases. This is the reason why you must now install Video DownloadHelper betas from this page.