Tilt! Downgrading firmware on the DCS-5020L

For those on Linux that use the DCS-5020L Pan & Tilt Wifi Camera: perhaps you don't want to upgrade the firmware to v1.15.12.

That update was published on 27 July 2018, but using it might break compatibility with Firefox. All you will see is this:

  "The browser you are using may have difficulty receiving images and
   video. If you experience any issues viewing this page, we suggest using
   Internet Explorer or Apple Safari."

It is possible to downgrade to v1.14.09 (available here). But not with Firefox. You can use Epiphany-browser to access the firmware menu, and upload the previous version.

You can also not use the DCS 5020L with Firefox 62. You must continue to use Firefox 52.9 ESR. In Debian, you can tell apt not to update firefox-esr:

  echo "firefox-esr hold" | dpkg --set-selections