Do you want to try another manual installation?

(1) Download a recent version for 64-bit Windows

• 10/29/2018: https://redirector.gvt1.com/edgedl/widevine-cdm/4.10.1146.0-win-x64.zip (newer date)
• 10/25/2018: https://redirector.gvt1.com/edgedl/widevine-cdm/4.10.1196.0-win-x64.zip (higher version)

If you can't download, the redirect might be blocked. Check whether any of your add-ons or any external software block redirects. You also could test downloading in another browser.

(2) Extract/install the contents of the ZIP archive into a folder in your profile

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

If you see a folder named gmp-widevinecdm, double-click into that folder.

If that folder does not exist, select and copy the folder name, then right-click a blank area of the list > New > Folder, then paste the folder name and click away. Then double-click into the new folder.

Select and copy the folder name, depending on which one you installed: 4.10.1146.0 or 4.10.1196.0

Right-click a blank area of the list > New > Folder, then paste the folder name and click away. Then double-click into the new folder.

Finally you can drop the contents of the ZIP archive here:

• LICENSE.txt
• manifest.json
• widevinecdm.dll
• widevinecdm.dll.lib
• widevinecdm.dll.sig

(3) Check preferences

Presumably Firefox will discover that new Widevine folder at your next startup, but possibly you would also need to create some settings.

Here are custom settings I see:

(A) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(B) In the search box above the list, type or paste wide and pause while the list is filtered

• media.gmp-widevinecdm.abi = x86_64-msvc-x64
• media.gmp-widevinecdm.version = 4.10.1146.0 or 4.10.1196.0, whatever your folder is named

If you have an older preference for version, you can double-click it and edit it to the new value.

If you need to create these preferences from scratch:

(i) Select and copy the name (ii) right-click a blank area of the list, click New, then String (iii) In the dialog that comes up, paste the name and click OK (iv) For the value, you can type the real value or just enter any character and click OK, then copy the real value, double-click to edit, and replace the temporary text with the real text and click OK

Hope that helps.

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

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

You can check the Browser Console for 'gmp' related messages about downloading Widevine (XHR needs to be selected).

See also:

• chrome://global/content/gmp-sources/widevinecdm.json