If the plug-ins are not installed with the installation / upgrade of the product you can install them manually. The extensions are provided with the installation.
To do that navigate to "C:\Program Files (x86)\Telerik\Test Studio\Browser Extensions\Firefox4+" and drag telerik_test_studio_automation-2016.x.xxx.x-fx-windows.xpi to a Firefox window.
Navigate to "C:\Program Files (x86)\Telerik\Test Studio\Bin\TestRecorderBrowserExtensions\Firefox" and drop telerik_test_studio_recorder-2016.x.xxx.x-fx-windows.xpi to a Firefox window.
Make sure that they are enabled at the end.
you can find more info about the extension troubleshooting.
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