Amazon Prime Video won't play.

You should be on 107.0.1, I have the same version macbook pro 10.13.6. https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

You may need a newer Widevine version.

Make sure you have updated the Widevine plugin to the latest version (4.10.2557.0).

• Tools -> Add-ons -> Plugins

You can toggle DRM off/on to see if that makes Firefox (re)load DRM components.

• Settings -> General: Play DRM
• https://support.mozilla.org/en-US/kb/enable-drm

You can possibly check the XHR requests in the Browser Console if this doesn't work.

• https://developer.mozilla.org/en-US/docs/Tools/Browser_Console

Thank you both for responding. Installing the latest version of the browser did the trick. Prior to posting my question, I checked "About Firefox". It informed me that I had 102 and that Firefox was up to date. Hence, my going no further down that road. Thanks again.

Mark it as resolved and enjoy.