Many keys found online are blacklisted or intended for specific OEM hardware versions, meaning they won't work on a standard installation. How to Get a Legitimate Key
Most "free key" websites bundle downloads with malware, adware, or ransomware.
Some USB tuners have the license key printed directly on a sticker attached to the device. Modern (and Better) Free Alternatives
Are you trying to get a specific working, or are you just looking for a general media player to handle old files?
A popular, free personal video recorder (PVR) for Windows that supports most TV tuners and offers a much cleaner interface than TotalMedia.
Visit the website of the company that made your TV tuner (e.g., MyGica, August, or KWorld). Many provide a "driver and software" pack for their specific devices that includes a licensed version of TotalMedia.